Richard Montiel v. Kevin Chappell ( 2022 )


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  •                 FOR PUBLICATION
    UNITED STATES COURT OF APPEALS
    FOR THE NINTH CIRCUIT
    RICHARD GALVAN MONTIEL,                  No. 15-99000
    Petitioner-Appellant,
    D.C. No.
    v.                       1:96-cv-05412-
    LJO-SAB
    KEVIN CHAPPELL, Warden, San
    Quentin State Prison,
    Respondent-Appellee.        OPINION
    Appeal from the United States District Court
    for the Eastern District of California
    Lawrence J. O’Neill, District Judge, Presiding
    Argued and Submitted April 16, 2021
    San Francisco, California
    Filed August 5, 2022
    Before: William A. Fletcher, Andrew D. Hurwitz, and
    Michelle T. Friedland, Circuit Judges.
    Opinion by Judge Friedland
    2                    MONTIEL V. CHAPPELL
    SUMMARY *
    Habeas Corpus/Death Penalty
    The panel affirmed the district court’s judgment denying
    Richard Galvan Montiel’s habeas corpus petition in which
    he challenged his California conviction and capital sentence
    for a 1979 robbery and murder.
    The California Supreme Court affirmed Montiel’s
    conviction and sentence on direct appeal and later summarily
    rejected “on the merits” Montiel’s state habeas petition.
    Montiel argued primarily that he was denied his Sixth
    Amendment right to effective assistance of counsel under
    Strickland v. Washington, 
    466 U.S. 668
     (1984), at his 1986
    penalty-phase trial. The district court certified two issues for
    appeal: first, whether his penalty-phase attorney, Robert
    Birchfield, rendered ineffective assistance of counsel by
    failing to present independent expert testimony from a
    psychopharmacologist that Montiel’s intoxication with
    phencyclidine (“PCP”) prevented him from being fully
    culpable for the crimes; and, second, whether Birchfield
    rendered ineffective assistance by failing to prepare defense
    witness Dr. Louis Nuernberger to testify regarding Montiel’s
    mental health. In addition to pressing those certified issues,
    Montiel argued that Birchfield was ineffective for failing to
    investigate and challenge the factual foundation for the
    opinion of prosecution expert Dr. Robert Siegel, and for
    failing to investigate and present evidence of Montiel’s
    psychosocial and family history to explain why he abused
    PCP and other drugs.
    *
    This summary constitutes no part of the opinion of the court. It
    has been prepared by court staff for the convenience of the reader.
    MONTIEL V. CHAPPELL                        3
    Applying Browning v. Baker, 
    875 F.3d 444
     (9th Cir.
    2017), the panel expanded the certificate of appealability to
    include the latter two claims, and considered whether
    Birchfield’s performance, considered as a whole, amounted
    to ineffective assistance of counsel at the 1986 penalty trial.
    Montiel argued that this court should review his
    Strickland claims de novo, because the California Supreme
    Court’s four-sentence denial of his claims “on the merits,”
    without issuing an order to show cause, signifies that the
    court concluded only that his petition did not state a prima
    facie case for relief such that there is no “adjudication on the
    merits” to which this court owes deference under the
    Antiterrorism and Effective Death Penalty Act (AEDPA), 
    28 U.S.C. § 2254
    (d). The panel disagreed, citing Cullen v.
    Pinholster, 
    563 U.S. 170
     (2011), in which the Supreme
    Court afforded AEDPA deference to the California Supreme
    Court’s summary denial of a habeas petition raising a
    Strickland claim—even though the state court had not issued
    an order to show cause. The panel therefore applied the
    deferential AEDPA standard, asking whether the denial of
    Montiel’s claims “involved an unreasonable application of”
    Strickland.
    The panel assumed, for the sake of argument, that the
    alleged errors constitute deficient performance under the
    first prong of Strickland. The panel held, however, under
    AEDPA's highly deferential standard of review, that the
    California Supreme Court could reasonably have concluded
    that Montiel's claim fails under the second prong of
    Strickland. The panel wrote that, comparing the mitigation
    evidence that was offered with what would have been
    offered but for Birchfield’s alleged errors, the state court
    could reasonably have decided that there was not a
    substantial likelihood that the jury would have returned a
    4                  MONTIEL V. CHAPPELL
    different sentence if Birchfield had not performed
    deficiently.
    The panel addressed uncertified issues in a memorandum
    disposition.
    COUNSEL
    David A. Senior (argued) and Matthew L. Weston, McBreen
    & Senior, Los Angeles, California; Saor E. Stetler, Mill
    Valley California; for Petitioner-Appellant.
    Julie A. Hokans (argued), Supervising Deputy Attorney
    General; Sean M. McCoy and Ivan P. Marrs, Deputy
    Attorneys General; Kenneth N. Sokoler, Supervising Deputy
    Attorney General; Michael P. Farrell and James William
    Bilderback II, Senior Assistant Attorneys General; Rob
    Bonta, Attorney General; Office of the Attorney General,
    Sacramento, California; for Respondent-Appellee.
    OPINION
    FRIEDLAND, Circuit Judge:
    In 1979, Richard Galvan Montiel was convicted by a
    California jury of the robbery and murder of Gregorio Ante,
    as well as the robbery of Eva Mankin. He was sentenced to
    death in 1986, following a penalty-phase retrial. The
    California Supreme Court affirmed Montiel’s conviction
    and sentence on direct appeal and later summarily rejected
    “on the merits” Montiel’s state habeas petition. Montiel
    filed a petition in federal district court for a writ of habeas
    corpus, which was denied.
    MONTIEL V. CHAPPELL                        5
    Montiel appeals the district court’s decision, arguing
    primarily that he was denied his Sixth Amendment right to
    effective assistance of counsel at his 1986 penalty-phase
    trial. The district court certified two issues for appeal: first,
    whether his penalty-phase attorney, Robert Birchfield,
    rendered ineffective assistance of counsel by failing to
    present independent expert testimony from a
    psychopharmacologist that Montiel’s intoxication with
    phencyclidine (“PCP”) prevented him from being fully
    culpable for the crimes; and, second, whether Birchfield
    rendered ineffective assistance by failing to prepare defense
    witness Dr. Louis Nuernberger to testify regarding Montiel’s
    mental health. In addition to pressing those certified issues,
    Montiel argues that Birchfield was ineffective for failing to
    investigate and challenge the factual foundation for the
    opinion of prosecution expert Dr. Robert Siegel, and for
    failing to investigate and present evidence of Montiel’s
    psychosocial and family history to explain why he abused
    PCP and other drugs. We expand the certificate of
    appealability (“COA”) to include those issues and therefore
    consider all arguments Montiel raises concerning whether he
    received ineffective assistance of counsel under Strickland
    v. Washington, 
    466 U.S. 668
     (1984), at his 1986 penalty trial.
    We address all four arguments related to Birchfield’s
    performance at the 1986 penalty trial as a single issue of
    ineffective assistance of counsel, in compliance with
    Browning v. Baker, 
    875 F.3d 444
     (9th Cir. 2017). We
    address that issue in this opinion. We decline to certify other
    issues for which Montiel seeks certification. We address
    those uncertified issues in a memorandum disposition that
    accompanies this opinion.
    We review the California Supreme Court’s denial of
    Montiel’s Strickland claims under the deferential standard
    6                  MONTIEL V. CHAPPELL
    required by the Antiterrorism and Effective Death Penalty
    Act (“AEDPA”). We may grant relief only if “the state
    court’s ruling on the claim being presented in federal court
    was so lacking in justification that there was an error well
    understood and comprehended in existing law beyond any
    possibility for fairminded disagreement.” Harrington v.
    Richter, 
    562 U.S. 86
    , 103 (2011). Although there is merit to
    Montiel’s Strickland claims, we conclude that the California
    Supreme Court’s ruling denying relief was not so lacking in
    justification that it meets that demanding standard. We
    therefore affirm the district court’s denial of habeas relief.
    I.
    A.
    At his 1979 trial, Montiel was represented by Eugene
    Lorenz. The focus of the defense was not to contest that, on
    January 13, 1979, Montiel had robbed Eva Mankin and
    killed Gregorio Ante. Rather, the defense’s primary
    argument was that Montiel’s intoxication with PCP and
    alcohol precluded him from forming the specific intent to
    commit the crimes.
    The following facts are consistent with the California
    Supreme Court’s summary in its decision on direct appeal
    from the 1979 guilt- and penalty-phase trials. See People v.
    Montiel (Montiel I), 
    39 Cal. 3d 910
    , 916–20 (1985).
    1. Prosecution’s Case
    On the morning of January 13, 1979, Montiel was sitting
    on the stairs outside his house when a neighbor who lived
    directly across the street, Eva Mankin, drove up to her home.
    Mankin began unloading grocery bags from her car, placing
    them on her front porch and setting her purse down next to
    MONTIEL V. CHAPPELL                            7
    them. As she returned to her car to close the doors, she saw
    Montiel approaching through her front yard accompanied by
    two small children. Montiel reached the porch before
    Mankin could enter the house. He told her that he had come
    over to help her carry the groceries inside. Mankin thanked
    him, refused, and asked him to leave, but Montiel repeated
    himself two more times and the final time “lowered his
    voice” and “said it in such a tone that [she] knew he meant
    it.” Mankin then opened the front door, and Montiel told
    each child to bring a bag into the house.
    After bringing the bags inside, the children left, but
    Montiel remained, standing about six feet inside the home.
    Mankin noticed that his eyes were “staring” and “glassy.”
    She asked him several times to leave but received no
    response, so she took him by the shirt and slowly led him
    outside. She went back inside the house and locked the door.
    Montiel then broke the glass in the door and reached in
    to unlock it. He re-entered the house as Mankin was calling
    the police. Montiel demanded her purse, grabbed it, and ran
    out of the house. The police later found Mankin’s purse in
    her car, missing two checkbooks, three bank books, and
    eight dollars in cash.
    Later that morning, Montiel arrived at the home of Victor
    Cordova. Victor lived with his wife, Maury Cordova,
    Maury’s sister Lisa Davis, and Lisa’s boyfriend, Tom
    Stinnett, among others. 1 Stinnett was in the front yard when
    1
    In Montiel I, the California Supreme Court spelled the Cordovas’
    last name as “Cardova” and spelled Maury’s name as “Maruy.” See, e.g.,
    
    39 Cal. 3d at 917
    . We use the spellings supplied by Victor Cordova at
    the 1986 penalty trial and adopted by the California Supreme Court in
    People v. Montiel (Montiel II), 
    5 Cal. 4th 877
     (1993). See, e.g., 
    id. at 899
    .
    8                     MONTIEL V. CHAPPELL
    Montiel arrived and walked into the house. Although Maury
    was acquainted with Montiel, Stinnett did not know him and
    followed him inside. Stinnett noticed that Montiel had a cut
    on his left arm by the wrist, and he helped Montiel clean and
    bandage the wound. In the process, he removed a piece of
    skin from Montiel’s arm with a razor blade. According to
    Stinnett, Montiel told him that he “did a purse snatch and
    went through a window.” Stinnett observed that Montiel
    seemed “jittery” and “shaky” and appeared to be under the
    influence of drugs. Montiel gave a checkbook to Maury,
    asking her to cash some checks and buy him some clothing.
    Maury refused, so Victor gave Montiel a change of clothes.
    Maury noted that Montiel was acting strange that
    morning. She testified that Montiel entered the house
    without knocking, which was unusual. She said that he was
    “more rowdy” than normal, “acted meaner,” and was “giving
    orders,” whereas before he had been “polite.”
    Lisa Davis did not know Montiel but testified that he
    acted “kind of weird.” At one point, Montiel tried to wipe a
    mole under her eye without explanation, and, later, he
    grabbed her arm and her purse and told her to get him some
    beer. 2
    2
    The prosecution’s witnesses gave varying responses about
    Montiel’s speech and movements that morning. Mankin noted that “[h]e
    walked slow” but said that she did not notice slurring in his speech or
    unevenness in his walk. Stinnett noted that Montiel was “talking fast,
    half of it was Spanish, half of it was English” but said that he noticed
    nothing unusual about Montiel’s walk or other movements, other than
    that Montiel appeared “nervous” and “shaky.” Maury did not notice
    anything unusual about Montiel’s eyes or the way he walked, and she
    said that his speech was not slurred. She did, however, note that he
    appeared to be under the influence of PCP. Victor testified that Montiel
    MONTIEL V. CHAPPELL                              9
    Eventually, Victor Cordova took Montiel by motorcycle
    to Montiel’s brother’s house. On the way, Victor’s
    motorcycle broke down. The men dismounted, and Victor
    pushed the motorcycle toward a nearby gas station. Victor
    called Maury from a payphone, asking her to pick them up,
    and began working on the motorcycle. At the same time,
    Montiel walked up the driveway of a nearby house. About
    ten minutes later, Montiel returned and told Victor that “he
    just killed a man,” and Victor testified that Montiel “made
    an expression like he killed him, like, you know, like you do
    a goat.” Montiel told Victor that he had left two beer cans
    in the man’s house and, in a threatening manner, asked
    Victor to retrieve them. Victor refused, so Montiel left and
    soon returned carrying a can of beer and a sack. 3
    About fifteen minutes later, Maury Cordova and Tom
    Stinnett arrived in a pickup truck. Victor and Stinnett loaded
    the motorcycle into the back of the pickup. Victor rode in
    the back with the motorcycle, and Montiel rode in the cab
    with Maury and Stinnett. According to Stinnett, Montiel
    said that “he cut some man’s head off” and that “he was the
    devil and a ride with him would be on top.” When they
    arrived at the Cordova’s house, Victor and Montiel went into
    “wasn’t making no sense” and “was high tempered,” and that Victor
    “knew he was messed up on PCP.” When asked about Montiel’s
    movements, Victor said that he “was walking different” and that “his
    coordination was off a little.” Davis said that “[h]is words were kind of
    stuttering, and they didn’t come out right.”
    3
    When asked to describe whether Montiel showed signs of PCP
    intoxication shortly after the murder, Victor described Montiel’s actions
    as “more or less the same” as before but said that “[h]e was talking more
    clearly.”
    10                    MONTIEL V. CHAPPELL
    a bedroom, where Montiel produced over $300 in twenty-
    dollar bills, as well as some pennies.
    Victor told Montiel to leave the house and called a taxi.
    Montiel “was still flipping out, still talking,” saying “[h]e
    was the devil.” When no taxi arrived, Victor drove Montiel
    to a motel and dropped him off. Later that day, Maury
    discovered a sack in her bedroom containing Mankin’s
    checkbooks, a large number of pennies, and a 12-inch
    “butcher knife” that was “covered in blood and had a broken
    handle.” 4 Maury and Stinnett washed off the knife and threw
    it into a nearby canal. Later that night, Montiel returned to
    the Cordovas’ house to ask about the knife, and Victor and
    Maury told him not to worry about it.
    The next day, the police contacted Victor. When Victor
    saw Montiel later that day and asked if he knew what he had
    done, Montiel nodded his head. Subsequently, Montiel told
    Victor that he was worried he might have left fingerprints on
    the telephone in the man’s house. Soon after, Victor left
    California to avoid testifying. He was arrested about two
    months later in Arizona as an accessory after the fact and
    returned to California to testify in exchange for immunity.
    The murder victim was a 78-year-old man named
    Gregorio Ante. At trial, his relatives testified to the
    following events. On the morning of the murder, Gregorio’s
    son Henry Ante arrived at his father’s house to help with
    some repairs and to help his daughter, who arrived soon
    after, move a piano that she was purchasing from Gregorio.
    4
    Stinnett also described seeing the paper sack containing “three or
    four dollars[’] worth of pennies, checkbooks, some bank statements,
    [and an] old rusted[-]up knife.” Davis also saw the items and testified
    that she later rolled up the pennies, counting seven dollars’ worth.
    MONTIEL V. CHAPPELL                     11
    Henry’s daughter paid Gregorio $200, and Henry saw
    Gregorio place the money in his left shirt pocket. Henry’s
    daughter drove away with the piano. Gregorio then gave
    Henry a twenty-dollar bill from the shirt pocket, after
    looking through his pants pockets and finding only a ten-
    dollar bill in the left pocket and two one-dollar bills in the
    right. Henry left, and as he went out the front door, he saw
    two men on a motorcycle in front of the house.
    David Ante, Gregorio’s grandson, arrived a short time
    later and found his grandfather’s body on the floor. The
    body was found in a pool of blood, with the left pocket of
    Gregorio’s pants pulled out. There was $180 in the left
    pocket of Gregorio’s “inside shirt,” which he wore
    underneath another layer, and no other money was found on
    his person. In his bedroom, the mattress had been moved off
    the bedframe, and the pennies that Gregorio collected were
    missing.
    The autopsy revealed two superficial wounds on
    Gregorio’s right cheek, two on the side of his neck, one on
    the lower neck, and one large, deep wound mid-neck,
    probably caused by at least two separate thrusts. The large
    wound was about seven inches wide and three inches deep.
    The cause of death was a hemorrhage with obstruction of the
    airway.
    A few days after Gregorio Ante’s death, Montiel was
    arrested and placed in a cell with an inmate named Michael
    Palacio. Palacio testified at trial that Montiel admitted to
    him that he had entered a man’s house to use a telephone.
    When Montiel hung up the telephone, an old man appeared
    and asked what he was doing. The man sat down in a chair,
    and Montiel saw money in the man’s shirt pocket. Montiel
    retrieved a knife from the kitchen, cut the man’s throat, and,
    according to Palacio, took approximately $200. In exchange
    12                   MONTIEL V. CHAPPELL
    for Palacio’s testimony, the State dismissed a felony charge
    against him for possession of marijuana while in state
    prison. 5
    Dr. Ronald Siegel testified at trial as an expert for the
    prosecution. 6        He     was    a    psychologist      and
    psychopharmacologist who worked with PCP and had
    published papers about its effect on behavior, and
    specifically on criminal behavior. Dr. Siegel explained that
    PCP was a drug that could have “a combination of different
    effects”—it could act as a stimulant, cause a loss of response
    to pain, produce an anesthetic reaction in sufficient doses,
    produce “extreme sensory reactions” like seizures, cause
    hallucinations, and trigger changes in perceptions, thinking,
    and mood. Dr. Siegel agreed that the effects of PCP are
    “extremely individualized.” While he acknowledged that it
    would be helpful to know how much of the drug someone
    had ingested to assess its effect on that person’s behavior,
    Dr. Siegel explained that “in the field of
    psychopharmacology, which is my field, the most important
    thing that we use is the actual behavior of the person as
    observed or witnessed by the people or themselves.”
    Dr. Siegel described the difference between PCP
    intoxication and PCP-induced psychosis. He explained that
    PCP psychosis refers to a mental state characterized by rapid
    changes in mood, paranoia, and a preoccupation with death
    or death-like thoughts, which can include a fixation on
    5
    Palacio admitted on cross-examination that he had read accounts
    of the crime in the newspaper before he approached the deputy sheriff
    with his offer to testify about Montiel’s confession.
    6
    The California Supreme Court gave only a brief summary of
    Dr. Siegel’s testimony in Montiel I. See 
    39 Cal. 3d at 919
    . We expand
    on that summary here.
    MONTIEL V. CHAPPELL                     13
    religious concepts like God or the devil. He testified that
    people in a state of PCP psychosis might also suffer from
    paranoid delusions or grandiose delusions (e.g., believing
    that they are capable of performing, and attempting to
    perform, “unrealistic feats of strength or other types of
    powers”).
    Dr. Siegel reviewed transcripts of the earlier trial
    testimony of Victor and Maury Cordova, Stinnett, Davis,
    and Palacio; the police reports containing interviews with the
    witnesses; the preliminary hearing transcript; and
    background psychological and counseling reports about
    Montiel. He also interviewed Maury, Stinnett, and Davis.
    Dr. Siegel opined that Montiel’s behavior was consistent
    with a low to moderate level of PCP in the blood but not
    consistent with PCP-induced psychosis. Dr. Siegel based his
    opinion on Montiel’s behavior at the time of the crimes,
    which indicated that Montiel was experiencing a state of
    hyper-excitation characterized by difficulty talking or
    slurred or stuttering speech, demanding and impulsive
    behavior, and glassy or dilated eyes. Dr. Siegel noted that
    most witnesses described Montiel as walking somewhat
    normally and that no one observed Montiel with two of the
    “signposts” of a high level of PCP intoxication—a flushed
    complexion (hypertension) and oscillation of the eyeballs
    (nystagmus). Dr. Siegel observed that Montiel was able to
    describe the killing of Gregorio Ante and recalled leaving
    beer cans in the house, which indicated that any amnesia was
    not severe, and noted that Montiel retained enough motor
    coordination to use the telephone and retrieve a large number
    of pennies without dropping them on the floor. Dr. Siegel
    further noted that, before the murder, Montiel was
    responsive to Maury Cordova’s directions as she and
    Stinnett assisted him with the cut on his arm and that, after
    14                 MONTIEL V. CHAPPELL
    the murder, Montiel insisted that he knew what was going
    on. In Dr. Siegel’s view, those statements suggesting
    Montiel’s lucidity further negated a conclusion of PCP
    psychosis.
    Dr. Siegel rejected the idea that Montiel’s statements
    about being the devil indicated that he was in a PCP-induced
    psychotic state. He noted that Montiel made those
    statements only after killing Gregorio Ante. According to
    Dr. Siegel, the timing suggested that the killing might have
    triggered an association causing Montiel to describe himself
    as the devil, but there was little to suggest that Montiel
    believed he was the devil before the killing or that such a
    hallucination caused him to kill.
    Dr. Siegel concluded that although Montiel was under
    the influence of PCP, his level of intoxication was not
    sufficient to diminish his capacity to form specific intent or
    to premeditate. Based on Palacio’s testimony, Dr. Siegel
    testified that Montiel had formed the intent to kill when he
    saw money in Gregorio Ante’s pocket. Finally, he opined
    that Montiel’s flight from the scene and expressions of
    concern the following day about possible evidence that he
    had left behind demonstrated his ability to reflect on the
    nature and consequences of his actions.
    2. Defense’s Case
    Montiel took the stand on his own behalf and testified to
    the following. Around the time of the events, he had been
    smoking three to four PCP cigarettes per day. On January
    13, 1979, he woke up, bought a six-pack of beer, and smoked
    a PCP joint. He felt a floating sensation from the PCP.
    When he saw Eva Mankin arrive at her house, something
    told him to help her with her groceries, so he ran to her house
    and carried the bags inside. His memory was spotty, but he
    MONTIEL V. CHAPPELL                     15
    recalled that he put his hand through the glass in her door
    and did not feel any pain. Mankin yelled and swung her
    purse at him, and he grabbed it. He walked away from the
    house and dropped the purse, and when various items fell
    out, he picked them up and placed the purse in her car. As
    he jogged away, he noticed checkbooks in his hand and
    decided to return them later.
    Montiel walked to the Cordovas’ house with a bloody
    arm, and as he approached, he saw three people out front,
    two of whom appeared to be wearing white uniforms. He
    said to them, “oh, you’re waiting for me, huh,” and then
    walked into the house. When Stinnett used the razor to cut
    the piece of skin off his arm, Montiel felt no pain.
    Montiel asked Victor to take him to his brother’s house.
    Before they left, he and Victor smoked a joint of PCP. On
    the way, they stopped at the liquor store, and Montiel bought
    two cans of beer. After the motorcycle broke down, Montiel
    walked to a house to use the telephone, and he remembered
    that his feet felt heavy. When he reached the door, he
    knocked but got no answer. He looked in through a window
    in the front door and saw a man lying in blood. He then
    returned to Victor and said that he had seen someone with
    his throat cut, not that he had cut someone’s throat.
    Montiel said that he relayed the same story to Stinnett,
    but Montiel testified that he did not remember telling anyone
    that he was the devil. According to Montiel, when Victor
    asked him the following day if he recalled what he had done,
    Montiel nodded “yes” because he assumed that Victor was
    asking about how he injured his arm. As to Palacio’s
    testimony regarding Montiel’s confession in jail, Montiel
    asserted that he only repeated to Palacio what the public
    defender had read him from the police report.
    16                  MONTIEL V. CHAPPELL
    Dr. Ronald Linder testified as an expert for the defense. 7
    Dr. Linder held a doctorate in education and health science
    and wrote his doctoral dissertation on drug abuse. He was
    involved in PCP research and had written numerous articles
    on PCP toxicity. Before testifying, Dr. Linder interviewed
    Montiel for two and a half hours and read transcripts of the
    earlier witnesses’ testimony at trial. Montiel described to
    Dr. Linder his extensive history of drug abuse, which began
    at a young age.
    Dr. Linder noted that many people experience a mind-
    body separation while using PCP and may feel that they have
    no control over what they see their body doing, even though
    their actions are dangerous to themselves or others. He said
    that the effects of PCP on behavior and mental state fluctuate
    rapidly and have only an attenuated relationship to the
    amount of the drug in the bloodstream. Dr. Linder opined
    that, as a result, Dr. Siegel could not reliably infer from
    Montiel’s behavior at one moment that Montiel had a low,
    moderate, or high level of PCP intoxication at another
    moment.
    According to Dr. Linder’s assessment, Montiel was
    significantly intoxicated before and during the crimes. He
    pointed to Montiel’s inability to feel pain after putting his
    hand through a glass window, his aggressive and impulsive
    behavior, and the killing itself and concluded that Montiel
    was in a “delusional state.” Dr. Linder noted that Montiel’s
    claims to be the devil were similar to other cases where PCP
    users had committed violent acts and described themselves
    or the victim as the devil. Dr. Linder discounted the absence
    of observed signs of hypertension or nystagmus, explaining
    7
    The California Supreme Court did not summarize Dr. Linder’s
    testimony in Montiel I. See 
    39 Cal. 3d at
    919–20. We do so here.
    MONTIEL V. CHAPPELL                       17
    that moderate hypertension might not cause an obviously
    flushed appearance and that nystagmus might not be
    noticeable to the untrained observer. In Dr. Linder’s
    opinion, Montiel’s level of intoxication would have
    prevented him from premeditating or weighing the
    considerations for and against killing.
    On cross-examination, Dr. Linder conceded that, if
    Montiel said that he had stolen a purse and taken checkbooks
    from it, one could infer from those facts that Montiel had an
    intent to steal. Dr. Linder clarified, however, that the effects
    of PCP were so unpredictable that a user could act rationally
    one minute and irrationally the next. Based on his judgment
    and knowledge of PCP, Dr. Linder opined that Montiel was
    not in a state that would “consistently allow him to
    premeditate.” Dr. Linder could assume only that Montiel
    was intoxicated with PCP but said he doubted that Montiel
    could have formed an intent to steal.
    3. Prosecution’s Rebuttal
    On rebuttal, prosecution witnesses testified that there
    was no window in Gregorio Ante’s front door and that an
    observer looking through an adjacent window could not have
    seen that Gregorio Ante’s throat was cut. The public
    defender testified that he had represented Montiel at his
    arraignment and acknowledged that he normally would not
    have supplied a defendant with a police report at the time
    indicated, and the prosecution’s investigator described how
    Palacio’s version of events contained information that was
    not in the police reports anyway.
    4. Verdict, First Penalty Re-trial, and Appeal
    The jury convicted Montiel of all counts and found two
    special circumstances that made Montiel eligible for the
    18                    MONTIEL V. CHAPPELL
    death penalty: that the murder occurred in the commission
    of a robbery (the felony-murder special circumstance) and
    that the murder was intentional and carried out for financial
    gain (the financial-gain special circumstance). The jury
    hung on the penalty. At a penalty re-trial, a second jury
    sentenced Montiel to death. On direct appeal, the California
    Supreme Court set aside the financial-gain special
    circumstance and reversed the death sentence because of two
    instructional errors. See Montiel I, 
    39 Cal. 3d at
    927–29.
    B.
    At a second penalty re-trial in 1986, Montiel was
    represented by Robert Birchfield. The Strickland claims
    certified for appeal in our court concern Birchfield’s
    performance. The following facts are consistent with the
    California Supreme Court’s summary in its decision on
    direct appeal from the 1986 trial. See Montiel II, 
    5 Cal. 4th 877
    , 898–904 (1993).
    1. Evidence of Gregorio Ante’s Murder
    Victor Cordova’s 1986 testimony was mostly consistent
    with his 1979 testimony, albeit with some differences. 8 For
    example, at the 1986 penalty trial, Victor admitted, contrary
    to what he said in 1979, that he and Montiel had shared a
    PCP joint between the Mankin robbery and their departure
    from the Cordovas’ house on Victor’s motorcycle. While
    Victor had described Montiel’s eyes only as “beady” and
    “glossy” at the 1979 trial, this time he remembered that
    “[t]hey were shifting back and forth real funny like” and
    8
    Eva Mankin and Henry Ante had died by the time of the 1986
    penalty trial, so their 1979 testimony was read to the jury. See Montiel
    II, 
    5 Cal. 4th at
    898 n.2 & 899 n.3. David Ante and Victor Cordova
    testified live.
    MONTIEL V. CHAPPELL                              19
    “wiggling” “in every direction.”          Victor echoed his
    testimony from 1979 that, after the killing, Montiel “said he
    did it just like you would do a goat,” but this time he recalled
    that Montiel had said the day before that he had recently been
    “slaughtering sheep[] or cows or something” at a ranch. And
    in the 1986 trial, Victor testified that, after the killing,
    Montiel had produced not only twenty-dollar bills but ones
    and fives as well. On cross-examination, Victor admitted
    that Montiel had recently asked him to lie on the stand to say
    that Montiel had smoked more PCP the morning of the
    crimes than he actually did.
    2. Evidence of Montiel’s Mental State and Intoxication
    Both parties introduced expert evidence about Montiel’s
    mental state and degree of intoxication on the morning of
    January 13, 1979.
    As it had done in the 1979 trial, the State presented
    expert testimony from Dr. Siegel. He testified that, in
    addition to the preparation he had conducted for Montiel’s
    first trial, he had since interviewed Montiel “to address the
    issue of his intoxication at the time of the commission of the
    offense.” 9 In that interview, Dr. Siegel obtained Montiel’s
    account of his history of drug use, his consumption of
    alcohol and PCP immediately before the crimes, and the
    crimes themselves. Dr. Siegel described Montiel’s account
    as follows: Montiel started sniffing glue and drinking around
    age twelve. He sniffed ten to fifteen tubes of glue per day
    until age seventeen or eighteen. By age nineteen, he would
    9
    Although Montiel had refused to speak with Dr. Siegel before his
    first trial, Dr. Siegel interviewed him in preparation for the first penalty
    re-trial in 1979 and relied on that interview for the opinions that he
    offered in the second penalty re-trial in 1986.
    20                 MONTIEL V. CHAPPELL
    drink all day. From age thirteen to his early twenties,
    Montiel reported heavy use of amphetamines, barbiturates,
    tranquilizers, cocaine, LSD, and heroin, resulting in
    addiction, hallucinations, overdoses, blackouts, and
    amnesia. He started smoking PCP at age twenty-three. By
    age twenty-nine, Montiel recounted drinking alcohol and
    smoking two to three joints of PCP daily.
    Dr. Siegel reviewed Montiel’s psychological reports
    from 1972 to 1978 and testified that they showed no gross
    psychopathology but did mention aggression, a potential for
    violence, false bravado, manipulation, and grandiosity.
    Montiel admitted during the interview that he had a quick
    temper and would get violent when he was intoxicated,
    “when provoked,” or “when it’s called for.” Montiel also
    admitted that he engaged in verbal arguments and fights
    when under the influence of alcohol, but he denied getting
    into serious fights or using weapons.
    Through Dr. Siegel, Montiel’s version of events and his
    reported confession to Michael Palacio were relayed to the
    jury. Dr. Siegel noted that Montiel reported drinking
    approximately one case of beer and smoking four to five
    PCP joints every day in January 1979. Montiel also reported
    that, on the morning in question, he woke up, smoked two
    PCP joints, and drank eight beers, after drinking alcohol and
    smoking PCP for most of the previous afternoon and
    evening. Dr. Siegel narrated the events of January 13 for the
    jury based on Montiel’s account, his interviews with
    witnesses, and the testimony of Palacio. This version of
    events included Palacio’s testimony that Montiel had
    confessed to killing Gregorio Ante after seeing money in the
    man’s pocket.
    Dr. Siegel opined that at the time of the crimes, there was
    no question that Montiel was “grossly intoxicated” from
    MONTIEL V. CHAPPELL                     21
    PCP and alcohol. Dr. Siegel acknowledged that PCP has
    unpredictable effects and that it can reduce impulse control,
    cause hallucinations and delusions, produce episodic partial
    amnesia, and exaggerate aggressive or violent tendencies.
    He further recognized that extended use of PCP can lead to
    a chronic mental disorder. Nonetheless, Dr. Siegel observed
    that Montiel appeared capable of goal-directed activity, as
    demonstrated by his response to certain events, such as being
    concerned about having left fingerprints on Gregorio Ante’s
    telephone, remembering the beer he left in Ante’s house, and
    searching the house for money. Dr. Siegel noted that
    Montiel knew he was smoking PCP and drinking alcohol,
    was aware he killed an old man, described the manner of
    killing, and identified the salient events accurately.
    Dr. Siegel concluded that, on the day and at the time of the
    murder, Montiel was not hallucinating or experiencing PCP-
    induced psychosis. Dr. Siegel confirmed that his opinion
    was the same as it had been in 1979: Montiel appeared to be
    aware of his actions even though he was intoxicated.
    The defense presented expert testimony from Dr. Louis
    Nuernberger, a psychiatrist formerly employed by the
    California Department of Corrections. Dr. Nuernberger had
    responsibility for inmate mental health concerns at San
    Quentin State Prison, and through his prison duties, acquired
    a familiarity with the drug and criminal histories of the
    inmates, which often included PCP use. Dr. Nuernberger
    had evaluated Montiel in 1979 or 1980, when Montiel first
    arrived on death row, to assess whether Montiel understood
    the nature of his sentence and the reasons for it.
    Dr. Nuernberger based his evaluation on an interview with
    Montiel, a report prepared by a psychologist, and a review
    of Montiel’s prison file.
    22                  MONTIEL V. CHAPPELL
    Dr. Nuernberger concluded that Montiel had a lifelong
    history of depression that led to his extensive drug abuse.
    Montiel’s progression fit into a pattern that Dr. Nuernberger
    observed in many inmates at San Quentin—glue-sniffing as
    a young teenager that progressed to PCP use, caused by
    depression in childhood. Dr. Nuernberger testified that, as a
    free man, Montiel engaged in drug abuse and violence, but
    when institutionalized, Montiel conformed his behavior to
    the expectations of the prison and was compliant.
    Dr. Nuernberger testified that Montiel’s use of PCP and
    alcohol likely eroded his faculties of judgment and self-
    control and that he was likely in a delirious state around the
    time of the crimes. In Dr. Nuernberger’s estimation,
    Montiel’s extended intoxication with PCP and alcohol were
    “directly responsible for the homicide,” and his sanity at the
    time of the offense was “severely impaired if not totally
    lacking.” Based on Montiel’s progression of drug use and
    the combination of alcohol and PCP he had consumed,
    Dr. Nuernberger questioned whether Montiel was capable of
    deliberate action at the time of the offenses.
    3. Prosecution’s Aggravating Evidence of Montiel’s
    Previous Crimes
    The prosecution introduced evidence in aggravation
    showing that Montiel had previously committed five other
    violent crimes, two of which resulted in convictions.
    •   First, law enforcement officers testified that,
    in 1968, they responded to a call about a fight
    at the Montiel household. According to the
    officers, Montiel and his brother Antonio
    fought after Montiel tried to hit his mother,
    Hortencia, in the head with a telephone, and
    Montiel then cut Antonio in the chest with a
    butcher knife. Montiel’s parents testified that
    MONTIEL V. CHAPPELL                     23
    they did not recall the incident and denied
    statements attributed to them in the police
    report. Antonio testified that he did not know
    whether Montiel had cut him.
    •   Second, another officer testified that, in 1969,
    Montiel’s then-wife, Rachel, reported that
    Montiel had hit her and had struck her sister
    in the abdomen while the sister was six
    months pregnant. Rachel testified, however,
    that her sister attacked Montiel and that
    Montiel never retaliated.
    •   Third, officers testified that, in 1971, they
    responded to an incident at the Kern County
    Fair when Montiel wrestled a stuffed animal
    from an older woman. After he failed to
    evade arrest, Montiel threatened to kill the
    officers’ wives and children and burn their
    homes.
    •   Fourth, two employees of a restaurant
    testified that, in 1972, Montiel brandished a
    small handgun or starter pistol, demanded
    money, fled with thirty dollars, and fired
    several shots at an employee who followed
    him outside. Montiel pleaded guilty to
    second       degree      robbery,     without
    enhancements for firearm or weapon use.
    •   Finally, a victim testified that, in 1973, he
    arrived home and caught Montiel stealing a
    television from his apartment. Montiel
    brandished a knife at him. Montiel pleaded
    guilty to misdemeanor burglary.
    24                 MONTIEL V. CHAPPELL
    Officers testified that it was customary to indicate in the
    police report whether the suspect appeared to be under the
    influence of drugs or alcohol, and that none of the reports of
    those prior crimes referred to any suspicion of intoxication.
    4. Montiel’s Mitigating Evidence
    The defense put on eighteen witnesses in addition to
    Dr. Nuernberger. The defense’s theory was that Montiel had
    a relatively normal upbringing but became unstable and
    erratic when he became a heavy PCP user. The defense
    argued that Montiel’s behavior was completely different
    when he was not under the influence of drugs, as
    demonstrated by his good conduct and rehabilitation in
    prison.
    Members of Montiel’s family testified that his family life
    was happy and that he was well-behaved and a good student
    until he started hanging out with the wrong crowd in high
    school and using drugs and alcohol. These witnesses
    indicated that Montiel was always respectful and nonviolent
    toward his parents, that family members visited him and
    exchanged letters with him while he was incarcerated, and
    that his family loved him. Rachel testified that, during their
    marriage, Montiel would sometimes become violent when
    drinking but said that he was a good father to their children,
    even after their separation.
    Montiel presented evidence of his history of drug abuse.
    Family members recounted a pattern of substance abuse
    beginning with glue sniffing in his teenage years and
    progressing to regular use of alcohol and PCP during
    adulthood. Regarding the events of January 13, 1979,
    Montiel’s sister Irene testified that he had smoked two PCP
    joints that morning. Other family members testified that he
    MONTIEL V. CHAPPELL                     25
    had been hallucinating and talking incoherently in the days
    leading up to the murder.
    Montiel presented evidence of his rehabilitation on death
    row. A prison chaplain testified that Montiel regularly
    attended voluntary religious services. A prison teacher said
    Montiel tried to improve his reading, writing, and
    mathematics skills and had made progress. A guard
    supervisor testified that Montiel presented no behavioral
    problems in San Quentin prison. A guard gave similar
    testimony about Montiel’s conduct in the Kern County jail.
    Montiel testified on his own behalf. He indicated that he
    had qualified for privileges on death row based on his good
    behavior. He confirmed the religious, educational, and
    artistic interests that he had developed in prison, and one of
    his paintings was admitted into evidence. Montiel indicated
    that, over time, he had developed empathy and remorse
    about Gregorio Ante’s murder, saying that he knew “what it
    feels like to lose a family member.” Montiel said that he
    would give his life to bring the victim back if that were
    possible.
    5. Penalty Verdict
    With the parties’ agreement, the trial court took judicial
    notice and advised the jury that the 1979 guilt-phase jury had
    found two special circumstances in connection with the
    murder: that the murder was intentional and carried out for
    financial gain (the financial-gain special circumstance) and
    that the murder was committed while Montiel was engaged
    in the commission of a robbery (the felony-murder special
    circumstance). The trial court did so despite the California
    Supreme Court’s decision in Montiel I that the financial-gain
    special circumstance was inapplicable. See Montiel II, 
    5 Cal. 26
                        MONTIEL V. CHAPPELL
    4th at 925–26. After three days of deliberations and five
    ballots, the jury sentenced Montiel to death.
    C.
    After the 1986 penalty trial, Montiel filed a timely notice
    of appeal. In 1993, the California Supreme Court affirmed
    his death sentence. Id. at 947. The court rejected, among
    other arguments, Montiel’s claim that Birchfield was
    ineffective for failing to prepare Dr. Nuernberger to testify,
    finding neither deficient performance nor prejudice. Id.
    at 923–25.     In dissent, Justice Mosk concluded that
    Birchfield rendered ineffective assistance of counsel when
    he “egregiously failed to prepare his case for life” without
    parole. Id. at 948 (Mosk, J., dissenting).
    Montiel filed a state habeas petition in the California
    Supreme Court. See People v. Romero, 
    8 Cal. 4th 728
    , 737
    (1994) (explaining that California’s constitution grants
    original jurisdiction in habeas corpus to the California
    Supreme Court). After requesting and receiving an informal
    response to the petition from the State and a reply from
    Montiel, the California Supreme Court denied the petition in
    1996. The four-sentence order stated: “The motion for
    judicial notice of the records in the underlying appeals is
    granted. The petition for writ of habeas corpus is denied.
    The delay in presentation of claims has been adequately
    explained. All claims are denied on the merits.” 10 In re
    10
    The order concluded with an unexplained citation to Harris v.
    Reed, 
    489 U.S. 255
    , 264 n.10 (1989) (stating that when a state court
    invokes a state procedural bar as a separate basis for its decision, a
    federal court may not review the state’s alternative holding on the merits
    of a federal claim). The State does not argue that the California Supreme
    Court rested its decision on a finding of procedural default, and we
    discern no reason to conclude that it did.
    MONTIEL V. CHAPPELL                            27
    Montiel, No. S033108, 
    1996 Cal. LEXIS 1048
    , at *1 (Cal.
    Feb. 21, 1996).
    In 1997, Montiel filed a 
    28 U.S.C. § 2254
     habeas petition
    in the United States District Court for the Eastern District of
    California. The district court denied the petition in 2014.
    Montiel timely appealed.
    II.
    We review de novo the district court’s denial of
    Montiel’s habeas petition. Sanders v. Cullen, 
    873 F.3d 778
    ,
    793 (9th Cir. 2017). Our review is circumscribed, however,
    by AEDPA. 11 Lambert v. Blodgett, 
    393 F.3d 943
    , 965 (9th
    Cir. 2004). AEDPA establishes a highly deferential standard
    for reviewing claims that a state court has “adjudicated on
    the merits.” 
    28 U.S.C. § 2254
    (d). In such cases, a federal
    court may not grant habeas relief unless the state court’s
    merits adjudication was “contrary to, or involved an
    unreasonable application of, clearly established Federal law,
    as determined by the Supreme Court of the United States,”
    
    id.
     § 2254(d)(1), or was “based on an unreasonable
    determination of the facts in light of the evidence presented
    in the State court proceeding,” id. § 2254(d)(2).
    Montiel argues that the California Supreme Court’s
    summary denial of his habeas petition means that his
    Strickland claims were not “adjudicated on the merits,” as
    that phrase is used in § 2254(d). His argument relies on the
    specifics of California’s habeas procedures.             Under
    California law, a habeas petitioner bears the initial burden of
    11
    Montiel filed his federal habeas application after April 24, 1996,
    so AEDPA applies to his case. Sully v. Ayers, 
    725 F.3d 1057
    , 1067 (9th
    Cir. 2013).
    28                 MONTIEL V. CHAPPELL
    pleading adequate grounds for relief and must support the
    factual allegations in his petition with any “reasonably
    available documentary evidence supporting the claim.”
    People v. Duvall, 
    9 Cal. 4th 464
    , 474 (1995). “An appellate
    court receiving such a petition evaluates it by asking
    whether, assuming the petition’s factual allegations are true,
    the petitioner would be entitled to relief.” 
    Id.
     at 474–75. “If
    no prima facie case for relief is stated, the court will
    summarily deny the petition. If, however, the court finds the
    factual allegations, taken as true, establish a prima facie case
    for relief, the court will issue an [order to show cause].” 
    Id. at 475
    . When an order to show cause issues, “the custodian
    of the confined person shall file a responsive pleading, called
    a return, justifying the confinement.” 
    Id.
     The petitioner then
    files a reply, called a traverse. 
    Id.
     at 476–77. If there are
    disputed factual issues to resolve, the court may order an
    evidentiary hearing. 
    Id. at 478
    . “Conversely, ‘[w]here there
    are no disputed factual questions as to matters outside the
    trial record, the merits of a habeas corpus petition can be
    decided without an evidentiary hearing.’” 
    Id.
     (alterations in
    original) (quoting People v. Karis, 
    46 Cal. 3d 612
    , 656
    (1988)).
    Montiel argues that the California Supreme Court’s four-
    sentence denial of his claims “on the merits,” without issuing
    an order to show cause, signifies that the court concluded
    that his petition did not state a prima facie case for relief.
    Montiel contends that, because the state court evaluated only
    whether he had stated a prima facie case, it never reached a
    decision on the underlying merits of his Strickland claims.
    Accordingly, he argues, there is no “adjudication on the
    merits” to which we owe AEDPA deference under
    § 2254(d), and we should review his Strickland claims de
    novo.
    MONTIEL V. CHAPPELL                             29
    We disagree. In Cullen v. Pinholster, 
    563 U.S. 170
    (2011), the Supreme Court afforded AEDPA deference to
    the California Supreme Court’s summary denial of a habeas
    petition raising a Strickland claim. 
    Id.
     at 187–88. In that
    case, as here, the state court denied the petition without
    issuing an order to show cause. 12 The Supreme Court
    acknowledged California’s procedural rules for state habeas
    petitioners, 
    id.
     at 188 n.12, but held that “[s]ection 2254(d)
    applies even where there has been a summary denial,” 
    id. at 187
    . The Court then undertook a full merits evaluation of
    the Strickland claim, which included “a thorough review of
    the state-court record,” 
    id. at 188
    ; see also 
    id.
     at 189–203,
    asking whether the California Supreme Court had
    “unreasonably applied clearly established federal law to
    [Pinholster’s] penalty-phase ineffective-assistance claim on
    the state-court record.” 
    Id. at 187
    . 13
    12
    In Pinholster, the California Supreme Court had summarily
    denied two separate state habeas petitions—one filed in 1993 and the
    other in 1997. See 
    563 U.S. at
    177–78 (referring to both petitions). In
    ruling on the 1993 petition, the California Supreme Court issued an order
    to show cause, but then vacated that order as “improvidently issued” and
    summarily denied the petition “on the substantive ground that it is
    without merit.” In re Pinholster, No. S034501, 
    1995 Cal. LEXIS 4500
    ,
    at *1 (Cal. July 19, 1995). In ruling on the 1997 petition, the California
    Supreme Court summarily denied the petition “on the substantive ground
    that it is without merit” without issuing an order to show cause. In re
    Pinholster, No. S063973, 
    1997 Cal. LEXIS 6194
    , at *1 (Cal. Oct. 1,
    1997).
    13
    Pinholster argued to the Supreme Court that the state court’s
    implicit determination—in summarily denying his petition without
    issuing an order to show cause—that Pinholster had not even made out
    a “prima facie” case for relief was contrary to, or an unreasonable
    application of, clearly established federal law. See Brief for Respondent
    at 52–53, Pinholster, 
    563 U.S. 170
     (No. 09-1088), 
    2010 WL 3738678
    (“[T]he California Supreme Court’s determination that Pinholster’s
    30                    MONTIEL V. CHAPPELL
    We therefore must decide whether the denial of
    Montiel’s claim “involved an unreasonable application of”
    Strickland. 14 See 
    28 U.S.C. § 2254
    (d)(1). Under that
    standard, Montiel must show “that ‘there was no reasonable
    basis’ for the California Supreme Court’s decision.”
    Pinholster, 
    563 U.S. at 188
     (quoting Harrington v. Richter,
    
    562 U.S. 86
    , 98 (2011)). In other words, Montiel must show
    that the state court’s ruling on the claim “was so lacking in
    justification that there was an error well understood and
    comprehended in existing law beyond any possibility for
    fairminded disagreement.” 15 Richter, 
    562 U.S. at 103
    .
    allegations, taken as true, failed even to make out a prima facie claim
    was not only wrong, it was objectively unreasonable. It follows that
    § 2254(d) does not prohibit a grant of relief on the ground that trial
    counsel rendered constitutionally ineffective assistance at the penalty
    phase of Pinholster’s capital trial.”). Yet, rather than evaluate only
    whether Pinholster had made out a prima facie case in his state habeas
    petition, the Supreme Court evaluated the full merits of Pinholster’s
    claims to assess whether the California Supreme Court could reasonably
    have denied habeas relief. See Pinholster, 
    563 U.S. at
    189–203. To the
    extent that Montiel makes a similar argument to the one Pinholster made,
    we must reject it. Pinholster teaches that we must evaluate Montiel’s
    Strickland claims in their entirety to determine whether the California
    Supreme Court could reasonably reject those claims on the merits.
    14
    Cannedy v. Adams, 
    706 F.3d 1148
     (9th Cir. 2013), does not
    support Montiel’s position. In Cannedy, we treated a summary denial
    from the California Supreme Court as an “adjudication on the merits”
    under § 2254(d) and therefore applied AEDPA to our review of the
    petitioner’s Strickland claim, evaluating the claim in light of the record
    before the California Supreme Court. Id. at 1155–57, 1162.
    15
    To the extent that Montiel also argues that de novo review is
    warranted because the California Supreme Court failed to hold an
    evidentiary hearing, we reject the argument. See Sully, 725 F.3d at 1067
    n.4 (holding that the California Supreme Court “does not fail to render
    an ‘adjudication on the merits,’” as contemplated by § 2254(d), “just
    because it does not grant an evidentiary hearing”). Montiel has not
    MONTIEL V. CHAPPELL                               31
    When reviewing a summary denial, we “look through” that
    judgment and apply the deferential standard to the last
    reasoned state court decision. See Wilson v. Sellers, 
    138 S. Ct. 1188
    , 1194–95 (2018); Ylst v. Nunnemaker, 
    501 U.S. 797
    , 803–04 (1991). Where there is no reasoned state court
    decision addressing a claim, we must consider what
    arguments or theories could have supported the state court’s
    summary denial, and then ask whether it is possible that fair-
    minded jurists could conclude that those arguments or
    theories are consistent with Strickland. Richter, 
    562 U.S. at 96, 102
    .
    III.
    A.
    We begin by addressing the scope of the issues that we
    will consider. The district court certified two issues for
    appeal: first, whether Birchfield rendered ineffective
    assistance of counsel by failing to present independent
    expert testimony that Montiel’s intoxication with PCP
    prevented him from harboring the mens rea necessary for the
    crimes; 16 and, second, whether Birchfield rendered
    pointed to any disputed factual issues in his state habeas petition that he
    claims necessitated an evidentiary hearing, so he has not shown any flaw
    in the fact-finding process or unreasonable determination of the facts.
    16
    Although the guilt-phase jury necessarily found, by convicting,
    that Montiel harbored the necessary mens rea for the crimes, Montiel’s
    mental state was still a relevant consideration for the 1986 penalty-phase
    jury. Under California law, a defendant is permitted to present evidence
    to the penalty-phase jury that there is lingering doubt as to his guilt, as a
    mitigating factor for consideration in sentencing. See People v. Terry,
    
    61 Cal. 2d 137
    , 147 (1964), overruled on other grounds by People v.
    Laino, 
    32 Cal. 4th 878
    , 893 (2004). The 1986 penalty-phase jury was
    also instructed under California’s death penalty law, which requires the
    32                    MONTIEL V. CHAPPELL
    ineffective assistance by failing to prepare Dr. Nuernberger
    to testify regarding Montiel’s mental health. Montiel also
    asks us to expand the COA to include two additional issues
    related to Birchfield’s performance at the 1986 penalty trial:
    whether Birchfield was ineffective for failing to challenge
    the factual foundation underlying Dr. Siegel’s expert
    opinion (specifically, Dr. Siegel’s reliance on Palacio’s
    testimony about Montiel’s confession) and whether
    Birchfield rendered ineffective assistance by failing to
    investigate and present evidence of Montiel’s psychosocial
    and family history to explain why he used PCP and other
    drugs.
    We expand the COA to include those issues. In
    Browning v. Baker, we held that a district court errs by
    limiting a COA to individual ineffective-assistance
    subclaims corresponding to particular instances of an
    attorney’s conduct within a single trial. 
    875 F.3d. 444
    , 471
    (9th Cir. 2017). Because the Sixth Amendment right “is a
    guarantee of effective counsel in toto,” we must “consider[]
    counsel’s conduct as a whole to determine whether it was
    constitutionally adequate.” 
    Id.
     Under Browning, therefore,
    we must consider the additional alleged errors in our
    analysis. With the COA so expanded, we consider the
    broader issue whether Birchfield’s performance, considered
    jury to consider certain enumerated mitigating circumstances in selecting
    between sentences of death and life without parole. See 
    Cal. Penal Code § 190.3
    . Evidence of Montiel’s mental state would have been relevant
    to several mitigating factors. Most relevant here, “factor (h) mitigation”
    requires the jury to consider “[w]hether or not at the time of the offense
    the capacity of the defendant to appreciate the criminality of his conduct
    or to conform his conduct to the requirements of law was impaired as a
    result of mental disease or defect, or the [e]ffects of intoxication.” 
    Id.
    § 190.3(h).
    MONTIEL V. CHAPPELL                      33
    as a whole, amounted to ineffective assistance of counsel at
    the 1986 penalty trial.
    For reasons we explain in a memorandum disposition
    filed concurrently with this opinion, we decline to expand
    the COA to include the other issues that Montiel advances in
    his opening brief.
    B.
    We now turn to whether Birchfield provided ineffective
    assistance of counsel at the 1986 penalty trial. To prove a
    Strickland claim, Montiel must show (1) “that counsel’s
    performance was deficient,” and (2) “that the deficient
    performance prejudiced the defense.”            Strickland v.
    Washington, 
    466 U.S. 668
    , 687 (1984). To establish
    deficient performance, “the petitioner must show that
    counsel’s representation ‘fell below an objective standard of
    reasonableness’ under ‘all the circumstances.’” Sully v.
    Ayers, 
    725 F.3d 1057
    , 1068 (9th Cir. 2013) (quoting
    Strickland, 
    466 U.S. at 688
    ). “To establish prejudice from
    counsel’s errors during the penalty phase of a capital case,
    the petitioner must show that ‘there is a reasonable
    probability that, absent the errors, the sentencer . . . would
    have concluded that the balance of aggravating and
    mitigating circumstances did not warrant death.’” 
    Id.
    (quoting Strickland, 
    466 U.S. at 695
    ). “A reasonable
    probability is a probability sufficient to undermine
    confidence in the outcome.” Cullen v. Pinholster, 
    563 U.S. 170
    , 189 (2011) (quoting Strickland, 
    466 U.S. at 694
    ). “That
    requires a ‘substantial,’ not just ‘conceivable,’ likelihood of
    a different result.” 
    Id.
     (quoting Harrington v. Richter,
    
    562 U.S. 86
    , 112 (2011)). “If the state court reasonably
    concluded that [Montiel] failed to establish either prong of
    the Strickland test, then we cannot grant relief.” Cannedy v.
    34                     MONTIEL V. CHAPPELL
    Adams, 
    706 F.3d 1148
    , 1157 (9th Cir. 2013) (footnote
    omitted).
    Montiel alleges that Birchfield’s performance at the
    1986 penalty trial was deficient because he failed to
    (1) present independent expert testimony from a
    psychopharmacologist that PCP prevented Montiel from
    forming a specific intent to commit robbery or murder;
    (2) adequately prepare Dr. Nuernberger to testify regarding
    Montiel’s mental health; (3) challenge Dr. Siegel’s reliance
    on Michael Palacio’s testimony that Montiel formed the
    intent to kill Gregorio Ante after seeing money in his shirt
    pocket; and (4) investigate and present evidence of Montiel’s
    psychosocial and family history. 17 We assume, for the sake
    of argument, that these alleged errors constitute deficient
    performance under the first prong of Strickland. We hold,
    however, under AEDPA’s highly deferential standard of
    review, that the California Supreme Court could reasonably
    have concluded that Montiel’s claim fails under the second
    prong of Strickland. Comparing the mitigation evidence that
    was offered with what would have been offered but for
    Birchfield’s alleged errors, the state court could reasonably
    have decided that there was not a substantial likelihood that
    the jury would have returned a different sentence if
    Birchfield had not performed deficiently. See Richter,
    
    562 U.S. at 102
     (holding that, when a state court issues a
    17
    The State argues that the sub-issue regarding Dr. Siegel’s reliance
    on the Palacio confession is not exhausted because it was not presented
    to the California Supreme Court and that, in any event, Montiel forfeited
    the claim by failing to raise the allegations in his federal habeas
    application. We need not decide whether the claim is unexhausted or
    forfeited because we conclude below that it fails. See 
    28 U.S.C. § 2254
    (b)(2) (“An application for a writ of habeas corpus may be denied
    on the merits, notwithstanding the failure of the applicant to exhaust the
    remedies available in the courts of the State.”).
    MONTIEL V. CHAPPELL                       35
    summary denial of a habeas claim on the merits, a federal
    habeas court must consider “what arguments or theories . . .
    could have supported[] the state court’s decision”).
    1.
    When a defendant has been convicted of first-degree
    murder with a special circumstance, California law allows a
    jury to impose a death sentence if it concludes that “the
    aggravating circumstances outweigh the mitigating
    circumstances.” 
    Cal. Penal Code § 190.3
    . The statute
    enumerates factors that the jury must consider, including the
    circumstances of the crime; the defendant’s involvement in
    previous criminal activity that involved the use of force or
    violence; any prior felony convictions; whether the
    defendant was under the influence of an “extreme mental or
    emotional disturbance”; and other circumstances that
    extenuate the gravity of the crime. 
    Id.
     § 190.3(a), (b), (c),
    (d), (k). Most relevant to this case, those factors also include
    so-called “factor (h) mitigation”: “Whether or not at the time
    of the offense the capacity of the defendant to appreciate the
    criminality of his conduct or to conform his conduct to the
    requirements of law was impaired as a result of mental
    disease or defect, or the [e]ffects of intoxication.” Id.
    § 190.3(h).
    In support of his state habeas petition, Montiel submitted
    mitigating evidence to the California Supreme Court that had
    not been presented at the 1986 penalty-phase trial.
    Specifically, he submitted declarations from his siblings
    Irene and Gilbert Montiel; his mother, Hortencia Montiel;
    clinical psychologist and psychosocial historian
    Dr. Gretchen White; clinical neuropsychologist Dr. Dale
    Watson; and psychiatrist Dr. Ferris Pitts. Below, we
    summarize the information provided in the declarations,
    36                 MONTIEL V. CHAPPELL
    which we assume could have been introduced at the 1986
    penalty-phase trial.
    a. Early Life
    Dr. White’s declaration provided an account of
    Montiel’s childhood. Montiel is from a family of migrant
    agricultural workers. Neither of his parents was educated
    past elementary school, and both grew up in poverty, in
    families with significant histories of alcoholism. His
    mother, Hortencia, suffered from paranoid delusions and
    believed strongly in hexes, witchcraft, and the supernatural.
    His father, Richard, suffered from alcoholism, was rarely
    home, would disappear for months at a time, and often ended
    up in jail for alcohol-related crimes. When Richard drank,
    he was verbally and physically abusive to Hortencia.
    Montiel spent much of his early life in the fields where
    he and his family worked. Hortencia worked in the fields
    while pregnant with Montiel “until the last minute before
    [she] gave birth.” As a toddler, Montiel would stay in the
    car or play in the fields while his parents were working.
    When Montiel was four or five years old, he started working
    in the fields with Richard from before dawn until the
    evening. They routinely worked in areas heavily sprayed
    with pesticides but were given no protective clothing or
    gloves, even when picking cotton, which left numerous cuts
    on their hands. Montiel and his siblings frequently returned
    home covered in pesticides—Montiel’s job was “to shake
    the trees so the fruit fell,” which left him “covered with the
    dust they put on the trees.” Montiel also harvested crops in
    fields adjacent to ones being sprayed and often would enter
    a field to continue working before the spray had settled;
    sometimes he worked as a “flagger,” standing in the field
    and signaling to the crop-dusting planes where to begin and
    end their runs, which also exposed him to the pesticides.
    MONTIEL V. CHAPPELL                     37
    Montiel often came home with irritated eyes, rashes, and
    headaches. In elementary school, Montiel started the school
    year late and was taken out of school for several weeks each
    fall to help pick fruit. He was embarrassed that everyone at
    school knew that he worked in the fields, and he was teased
    for being so poor.
    Montiel’s family lived in extreme poverty. Every
    summer, they lived in labor camps near the fields, in a tent
    with a dirt floor and no electricity or running water. When
    Montiel was almost four years old, the family moved into a
    one-bedroom house in Bakersfield next door to a cattle yard
    and slaughterhouse. The stench was overwhelming, and the
    house was infested with flies. It had no electricity and had
    running water only from a faucet in the front yard. The
    family sometimes went several days without food, subsisting
    on a mixture of flour, sugar, and water. Hortencia eventually
    received welfare assistance, on which the family depended.
    Montiel had one older half-sibling and five younger siblings,
    all but one of whom suffered from serious substance abuse,
    failed in school, and later spent time in jail or prison.
    Montiel’s drug abuse started early and progressed to
    dangerous levels by early adulthood. He began sniffing glue
    around age ten and used five or six tubes every day. He
    sniffed glue whenever he did not want to deal with “bad
    times,” as when his father was gone or when the family ran
    out of money. By the time Montiel was sixteen or seventeen,
    he was sniffing glue less frequently, but he drank more
    alcohol and began abusing other drugs, including LSD and
    various prescription pills sold on the streets. When Montiel
    was twenty, he was taking about ten prescription pills per
    day. By 1972, at twenty-three years old, Montiel was
    injecting heroin four times a day and had been hospitalized
    three times for drug overdoses. In his late twenties, Montiel
    38                MONTIEL V. CHAPPELL
    started using PCP. His siblings Gilbert and Irene, both of
    whom also used drugs heavily, remarked that Montiel acted
    like a different person on PCP, noting, among other strange
    behaviors, that PCP would cause him to talk about magic and
    the supernatural.
    Montiel’s drug abuse caused him to struggle in school
    and eventually led to repeated arrests and incarceration.
    Montiel first went to juvenile hall when he was eleven years
    old for breaking into school and stealing ice cream and fruit
    cocktail. He was sent to a juvenile camp at age twelve for
    sniffing glue. He rarely received good grades and failed 9th
    and 10th grades before dropping out of school. From 1972
    through 1977, during his twenties, Montiel was never out of
    state custody for more than a sixty-day period.
    Montiel never learned to cope with depression or
    feelings of abandonment. His parents did not model
    constructive ways of dealing with stressors or difficulties;
    rather, to deal with psychological pain, Montiel’s father
    turned to alcohol or left the home, and his mother turned to
    magic and witchcraft. From childhood through early
    adulthood, Montiel experienced loss and abandonment not
    only as a result of his father’s disappearances and his
    mother’s inability “to provide minimal parenting for [him],”
    but also due to the deaths of his infant daughter, two of his
    brothers, and several friends.
    b. Mental Health
    After his arrest for the 1979 offenses, Montiel was
    evaluated by several mental health professionals. One
    psychiatrist observed that Montiel was “chronically
    depressed and ‘mind damaged,’ if not brain damaged, by his
    extensive drug use.”      The evaluations reflected that
    Montiel’s “serious depression manifested as a cyclical
    MONTIEL V. CHAPPELL                      39
    pattern of poor behavioral control” and that he had
    “deficits[] in judgment, self-control, and social skills as a
    consequence of toxic substance abuse, especially glue-
    sniffing, paint sniffing, and the continued use of PCP.”
    In 1993, Dr. Watson, the clinical neuropsychologist,
    evaluated Montiel and opined that he “suffers from cognitive
    and neuropsychological deficits and probable brain
    dysfunction,” that he “functions at the level of borderline
    intelligence,” and that he “is impaired by significant learning
    disabilities and very severe attention/concentration deficits
    (in the mildly retarded range).” Dr. Watson concluded that
    the onset of these deficits “dates at least from adolescence,”
    based on Montiel’s inability to perform at age-appropriate
    levels in reading and arithmetic. Dr. Watson concluded that
    Montiel’s chronic inhalation of the neurotoxin toluene
    (found in glue) likely caused diffuse brain damage. Related
    impairments and neuropsychological deficits resulted in
    “poor planning skills,” being “vulnerable to misinterpreting
    his environment with consequent manifestations of
    inappropriate and ill-modulated behavior,” and having
    “difficulty in making judgments that require deliberation and
    consideration of abstract consequences.” These deficits
    would be further exacerbated by alcohol or drug
    intoxication.
    c. Effects of PCP
    Dr. Pitts, the psychiatrist, stated that PCP is a
    “dissociative anesthetic, which means that it impairs normal
    cognitive brain function” and causes bizarre and impulsive
    behaviors, including spontaneous violence. Dr. Pitts opined
    that when Montiel took Mankin’s purse, he was acting on
    “sheer impulse” because the PCP prevented him from
    evaluating his behavior or making any moral judgments.
    Dr. Pitts noted that the fact that Montiel remained close to
    40                MONTIEL V. CHAPPELL
    Gregorio Ante’s house and in plain sight immediately after
    the killing illustrated Montiel’s “lack of cognitive
    functioning at the time of the homicide.” Dr. Pitts also
    placed greater significance than Dr. Siegel had on Montiel’s
    reported statements, following the murder, that he was the
    devil. According to Dr. Pitts, those statements strongly
    suggested that Montiel actually believed himself to be the
    devil, particularly when viewed in the context of his
    mother’s beliefs in the supernatural and the evidence that
    Montiel had spoken of being the devil or talking to the devil
    in the two weeks before the murder. Contrary to Dr. Siegel’s
    opinion, Dr. Pitts believed that Montiel was unable to harbor
    specific intent to steal or murder or to premeditate because
    he was in a dissociative animated state and was behaving “at
    the level of primitive reflex.”
    2.
    To assess prejudice under Strickland’s second prong in a
    capital case, we must “reweigh the evidence in aggravation
    against the totality of available mitigating evidence.”
    Pinholster, 
    563 U.S. at 198
     (quoting Wiggins v. Smith,
    
    539 U.S. 510
    , 534 (2003)). That analysis requires us to
    “compare the evidence that actually was presented to the
    jury with the evidence that might have been presented had
    counsel acted differently.” Clark v. Arnold, 
    769 F.3d 711
    ,
    728 (9th Cir. 2014) (quoting Murtishaw v. Woodford,
    255¸F.3d 926, 940 (9th Cir. 2001)).
    We consider first the new evidence from the declaration
    of Dr. Pitts regarding Montiel’s diminished capacity from
    the effects of PCP at the time of the crimes. Some of that
    evidence would have been cumulative of the concessions
    that Birchfield extracted from Dr. Siegel and the testimony
    that Birchfield elicited from Dr. Nuernberger. For example,
    the jury knew from the expert testimony presented at trial
    MONTIEL V. CHAPPELL                     41
    that PCP was a dissociative drug with unpredictable effects
    that could erode faculties of judgment and self-control.
    Dr. Siegel acknowledged that chronic use of PCP could
    cause delusional episodes. Dr. Nuernberger opined that
    Montiel was likely in a state of “toxic delirium” around the
    time of the crimes, considered Montiel’s intoxication with
    PCP and alcohol to be “directly responsible for the
    homicide,” and believed that Montiel’s sanity at the time of
    the offense was “severely impaired if not totally lacking.”
    The jury also knew—from the testimony of Montiel, his
    family members, and Dr. Siegel—that Montiel had
    consumed a significant amount of PCP in the days leading
    up to and on the morning of the murder, and that he had been
    hallucinating and behaving strangely.           The primary
    contribution of the declaration from Dr. Pitts was his bottom-
    line conclusion that Montiel’s use of PCP made him unable
    to harbor the specific intent for robbery or murder, but given
    Dr. Siegel’s concessions, a reasonable jurist could view that
    conclusion as a relatively marginal addition to Montiel’s
    case for “factor (h) mitigation.”
    The new expert testimony must also be viewed in light
    of the considerable evidence suggesting that Montiel was
    aware of his actions. As the California Supreme Court
    observed in rejecting one of Montiel’s challenges to his
    sentence on direct appeal:
    The manner of killing suggested calculation
    and awareness. It was also clear that
    [Montiel] had ransacked Gregorio’s
    residence and taken money. Moreover,
    Victor testified that moments after the crime,
    [Montiel] described it several times in
    graphic and coherent terms. Victor also
    indicated that [Montiel] carried away the
    42                 MONTIEL V. CHAPPELL
    murder weapon and immediately returned to
    the house to retrieve other evidence which
    might link him to the homicide. [Montiel]
    continued to boast about the killing as he was
    driven away from the scene. He later asked
    Victor to lie about the extent of his
    intoxication.
    Montiel II, 
    5 Cal. 4th at 921
    . The evidence concerning the
    Mankin robbery was similarly suggestive: Montiel fled
    Mankin’s home with her stolen purse and apparently had the
    presence of mind to remove the items of value—a
    checkbook, several bank books, a knife, and some cash—
    before discarding the purse. A reasonable jurist could
    conclude that Dr. Pitts’s opinion that Montiel was acting on
    the level of “primitive reflex” would have been unlikely to
    sway the jury, considering the circumstantial evidence that
    Montiel was making decisions that reflected awareness and
    at least some degree of rationality.
    For similar reasons, a reasonable jurist could discount
    the prejudicial impact of Birchfield’s failure to challenge
    Dr. Siegel’s partial reliance, in forming his opinion, on the
    apparently erroneous testimony of Michael Palacio. In his
    1986 penalty-phase trial testimony, Dr. Siegel narrated the
    events of January 13 as he understood them, based on his
    interviews with witnesses and his review of the 1979 guilt-
    phase trial transcripts. At the end of Dr. Siegel’s narrative,
    the prosecution asked whether he had considered Palacio’s
    testimony about Montiel’s confession in jail. Dr. Siegel
    responded affirmatively and stated:
    A: According to testimony from Michael
    Palacio, Mr. Montiel had entered the
    house, wanted to use the telephone and
    MONTIEL V. CHAPPELL                       43
    noticed some money sticking out of this
    old man’s pocket. At that point went into
    the kitchen to get a knife.
    Q: For what purpose?
    A: With the intent to kill him, according to
    Michael Palacio, that he formed the intent
    to kill him when he saw the old man with
    the money.
    Palacio’s version of events was inaccurate—the $180
    that Gregorio Ante received from the piano sale and placed
    in his front shirt pocket was recovered on his body,
    suggesting that Montiel did not form the intent to kill Ante
    after deciding to steal that money. Montiel now contends
    that Palacio’s false testimony formed the predicate for
    Dr. Siegel’s conclusion that Montiel was capable of “goal-
    directed activity,” and that Birchfield’s failure to object or to
    effectively cross-examine Dr. Siegel prejudiced Montiel’s
    defense.
    The California Supreme Court rejected a similar
    argument on direct appeal, noting that, even without
    Palacio’s testimony, there was a wealth of circumstantial
    evidence that Montiel knew what he was doing. Montiel II,
    
    5 Cal. 4th at 921
    . Indeed, Palacio’s testimony was only one
    of several factors that led Dr. Siegel to conclude that Montiel
    had the capacity to understand the nature of his conduct—
    other factors included, for example, Montiel’s concern that
    he had left behind evidence connecting him to the crime and
    his search of the house for money.
    Besides, Birchfield did take steps to undermine the
    narrative offered by Dr. Siegel, prompting the prosecution to
    present an alternative theory of the robbery-murder.
    44                 MONTIEL V. CHAPPELL
    Specifically, Birchfield presented testimony from an
    investigator with the Kern County Sheriff’s Office, who
    clarified for the jury that $180 was found on Ante’s body, in
    a front T-shirt pocket that was concealed by an outer layer.
    On cross-examination, the prosecution showed the jury a
    close-up photograph of Ante’s pants pockets—which,
    according to Ante’s son Henry, had contained $12 in bills of
    small denominations on the morning of the murder—and the
    investigator confirmed that those pants pockets were found
    empty when investigators arrived at the scene. A reasonable
    jurist could conclude, therefore, that the jury was aware of
    the flaw in the narrative offered by Palacio and repeated by
    Dr. Siegel—but that the jury nonetheless concluded that
    Montiel had intentionally killed Ante in the process of
    robbing him of the money in his pants pockets, even if not
    for the money in his shirt pocket.
    That leaves Montiel’s psychosocial history and mental
    health evidence. Some of this evidence would have been
    cumulative. For example, the jury already knew that
    Montiel started sniffing glue at a young age before turning
    to heavier drugs. In addition, Dr. Nuernberger had offered
    the opinion, albeit without much substantiating detail, that
    Montiel’s drug use stemmed from a deep-seated, lifelong
    depression and had described Montiel’s compliant behavior
    in the controlled, drug-free prison environment.
    Still, much of the psychosocial history was new, and that
    history presented a starkly different narrative than the story
    of a relatively normal childhood that Birchfield presented to
    the jury. A complete picture of Montiel’s childhood would
    have helped the jury understand that Montiel’s behavior as
    an adult was not, as the prosecution put it, “a conscious
    choice for his life, for violence, greed, and drug use.”
    Rather, the jury would have understood that Montiel’s
    MONTIEL V. CHAPPELL                             45
    criminal behavior was rooted in early traumatic experiences
    and the impoverished conditions of his upbringing. 18 The
    new mental health evidence also offered a non-cumulative
    and more robust assessment of Montiel’s cognitive and
    neuropsychological deficits, which the jury could have
    considered in mitigation. See Boyde v. California, 
    494 U.S. 370
    , 382 (1990) (“[E]vidence about [a] defendant’s
    background and character is relevant [at sentencing] because
    of the belief, long held by this society, that defendants who
    commit criminal acts that are attributable to a disadvantaged
    background, or to emotional and mental problems, may be
    less culpable than defendants who have no such excuse.”
    (emphasis omitted) (quoting Penry v. Lynaugh, 
    492 U.S. 302
    , 319 (1989), abrogated on other grounds by Atkins v.
    Virginia, 
    536 U.S. 304
    , 320 (2002))).
    We assume that Birchfield’s failure to present to the jury
    this more sympathetic picture of Montiel’s childhood
    suffering constituted deficient performance. But we cannot
    say that the California Supreme Court would have been
    unreasonable in holding that the error did not prejudice the
    defense sufficiently to undermine confidence in the outcome
    of the penalty-phase trial. The prosecution’s case in
    aggravation was relatively strong, showing that Montiel had
    engaged in a prior pattern of violence, with one incident
    resulting in a felony conviction. The jury was also aware of
    the gruesome nature of the murder and was instructed that
    18
    In support of his state habeas petition and this appeal, Montiel
    provided a declaration from Dr. Thomas Milby about the medical effects
    of pesticide exposure. Montiel does not dispute that he failed to present
    this declaration to the district court, and his arguments on appeal do not
    appear to rely on the declaration. We therefore do not consider it.
    46                     MONTIEL V. CHAPPELL
    the 1979 guilt-phase jury had found felony-murder and
    financial-gain special circumstances. 19
    Montiel relies on Rompilla v. Beard, 
    545 U.S. 374
    (2005), Wiggins v. Smith, 
    539 U.S. 510
     (2003), and Bean v.
    Calderon, 
    163 F.3d 1073
     (9th Cir. 1998), but we are not
    persuaded by his comparisons. In all three of those cases,
    the court was not bound to apply AEDPA deference in its
    prejudice analysis and thus conducted its inquiry de novo
    before granting habeas relief. Rompilla, 
    545 U.S. at 390
    ;
    Wiggins, 
    539 U.S. at 534
    ; Bean, 
    163 F.3d at 1077
    . The issue
    before us is not whether we would have reached a different
    conclusion in this case on de novo review, but rather whether
    we can reach such a conclusion under AEDPA’s standard of
    review. “Even if we would grant federal habeas relief upon
    de novo review, § 2254(d) precludes such relief if there are
    ‘arguments that would otherwise justify the state court’s
    result.’” Sully, 725 F.3d at 1067 (quoting Richter, 
    562 U.S. at 102
    ). For the reasons above, we conclude that such
    arguments exist here.
    19
    As previously noted, the California Supreme Court had set aside
    the financial-gain special circumstance on direct appeal before reversing
    Montiel’s death sentence from the first penalty re-trial on other grounds.
    Montiel I, 
    39 Cal. 3d 910
    , 927–29 (1985). Notwithstanding that
    decision, the trial court, with the parties’ consent, improperly instructed
    the 1986 penalty-phase jury that the guilt-phase jury had found the
    financial-gain special circumstance. See Montiel II, 
    5 Cal. 4th at
    925–
    26. The California Supreme Court addressed the prejudicial impact of
    the error in Montiel II, concluding that the mistake did not undermine
    confidence in the judgment. 
    Id.
     at 925–26 & 926 n.20. The court
    explained that nothing in its previous decision striking the financial-gain
    special circumstance “precluded this penalty jury from learning that its
    predecessor found an intentional killing.” 
    Id.
     The California Supreme
    Court’s conclusion that the error probably had a minimal impact on the
    prosecution’s case in aggravation was reasonable.
    MONTIEL V. CHAPPELL                     47
    Montiel also cites Porter v. McCollum, 
    558 U.S. 30
    (2009) (per curiam), in which the Supreme Court found
    prejudice under AEDPA’s deferential standard. But that
    case is distinguishable. In Porter, the prosecution’s case for
    aggravation consisted only of the circumstances surrounding
    the crimes themselves—Porter had no other criminal history.
    The defense put on virtually no case for mitigation: “The
    judge and jury at Porter’s original sentencing heard almost
    nothing that would humanize Porter or allow them to
    accurately gauge his moral culpability.” 
    Id. at 41
    . A proper
    investigation would have uncovered evidence that Porter
    was a decorated war hero who suffered from PTSD as a
    result of his combat experience, that Porter’s childhood
    included a history of physical abuse, and that Porter suffered
    from neurological deficits that impaired his ability to
    conform his conduct to the law. 
    Id.
     at 33–37. Here, by
    contrast, the prosecution’s case for aggravation was
    substantial, and, notwithstanding the alleged errors made by
    Birchfield, the jury did hear substantial mitigation
    presentation, including testimony from nineteen witnesses.
    In short, weighing the aggravating circumstances against
    the totality of the mitigating evidence—and applying, as we
    must, AEDPA’s very deferential standard of review—we
    hold that a reasonable jurist could conclude that Montiel
    failed to establish prejudice from Birchfield’s errors.
    IV.
    For the foregoing reasons, we conclude that the
    California Supreme Court’s summary denial of Montiel’s
    ineffective assistance of counsel claims was not an
    unreasonable application of Strickland. We therefore
    AFFIRM the judgment of the district court denying
    Montiel’s application for a writ of habeas corpus.