United States v. Andres Mencia ( 2021 )


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  •          USCA11 Case: 18-13967      Date Filed: 06/09/2021     Page: 1 of 33
    [DO NOT PUBLISH]
    IN THE UNITED STATES COURT OF APPEALS
    FOR THE ELEVENTH CIRCUIT
    ________________________
    No. 18-13967
    ________________________
    D.C. Docket No. 0:17-cr-60301-WPD-1
    UNITED STATES OF AMERICA,
    Plaintiff-Appellee,
    versus
    ANDRES MENCIA,
    Defendant-Appellant.
    ________________________
    Appeal from the United States District Court
    for the Southern District of Florida
    ________________________
    (June 9, 2021)
    Before MARTIN, GRANT, and BRASHER, Circuit Judges.
    BRASHER, Circuit Judge:
    This is Andres Mencia’s direct appeal of his conviction for conspiracy to
    violate the Controlled Substances Act, 
    21 U.S.C. § 841
    (a), by dispensing controlled
    substances without a legitimate medical purpose in the usual course of professional
    practice, in violation of 
    21 U.S.C. § 846
    . Mencia, a licensed physician, owned and
    USCA11 Case: 18-13967        Date Filed: 06/09/2021   Page: 2 of 33
    operated a geriatric specialty clinic where many patients, often younger and addicted
    to drugs, would pay cash in exchange for narcotic prescriptions. Mencia argues that
    (1) there was insufficient evidence to support his conviction, (2) the district court
    abused its discretion in making certain evidentiary rulings, and (3) the Controlled
    Substances Act is unconstitutionally vague as applied to physicians. We disagree.
    The government presented overwhelming evidence of Mencia’s guilt, the district
    court did not abuse its discretion, and this Court has already held that the Act is not
    unconstitutional as applied to physicians. Accordingly, we affirm.
    I.     BACKGROUND
    Andres Mencia, a formerly licensed physician, owned and practiced at Adult
    & Geriatric Institute of Florida, Inc., in Oakland Park, Florida. Although AGI was
    not a pain clinic and Mencia was not a pain specialist, a significant amount of his
    business came from prescribing opioids and other controlled substances to certain
    patients who paid in cash. Mencia called those individuals “Code-G” patients, with
    the “G” standing for “gypsy,” because they did not have insurance. Even though
    other patients also paid in cash, Code-G patients never paid at the checkout counter.
    Instead, Mencia assigned certain medical assistants to collect their payments.
    Mencia often prescribed these Code-G patients a combination of Percocet, Xanax,
    and Soma, which one of the government’s experts, Dr. Sanford Silverman, described
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    as the “holy trinity”––a trio consisting of an opioid, benzodiazepine, and a muscle
    relaxant that drug-seeking patients often request.
    Between January 1, 2014, and May 31, 2018, Mencia prescribed controlled
    substances to around 45,000 patients. Around one-third of those patients paid in
    cash. Those patients who were covered by Medicare or commercial insurance often
    received more prescriptions than just the “holy trinity”; they would also receive
    Dilaudid, Oxycontin, or amphetamines. And Mencia consistently prescribed the
    highest possible dose strength of controlled substances, including oxycodone and
    Xanax.
    One patient, JH, returned monthly for controlled substance prescriptions after
    Mencia initially diagnosed him with back pain without an examination. JH’s
    girlfriend and grandmother each called the front desk at AGI to inform them that JH
    was an opioid addict, but Mencia continued to prescribe him oxycodone and Soma.
    In fact, Mencia continually increased JH’s doses and even gave him refills when JH
    claimed that his prescriptions had been stolen. JH eventually fatally overdosed on
    oxycodone and Xanax.
    Oscar Luis Ventura-Rodriguez, one of Mencia’s medical assistants, testified
    that when he first started at AGI, Mencia would spend some time with Code-G
    patients and then Ventura-Rodriguez would write them prescriptions, which Mencia
    would sign. The majority of those prescriptions were for Percocet. But Mencia never
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    physically examined those patients, and the consultations usually only lasted around
    ten minutes.
    Over time, the number of Code-G patients increased, and Mencia stopped
    entering the room at all when returning patients came in. Instead, medical assistants
    would look up what prescriptions the patients had previously been given, fill the
    prescriptions out the same way as before, then take them to Mencia to sign. The
    patients would receive those controlled substance prescriptions without an
    examination and without any physician reviewing whether the medications were
    medically necessary.
    The price that AGI charged Code-G patients also increased over time. And
    Mencia instructed his assistants to get those patients out of the waiting room as soon
    as they arrived. Although Mencia instructed his medical assistants to ask Code-G
    patients for MRIs, not having one did not affect their ability to get a prescription for
    controlled substances.
    Ventura-Rodriguez testified that, as the number of Code-G patients increased,
    Mencia began instructing him and other assistants on which medications and how
    many pills to prescribe before patients ever arrived. At that point, Ventura-
    Rodriguez began to suspect that many Code-G patients were not truly in pain. He
    shared that suspicion with Mencia, but Mencia continued to sign the controlled
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    substance prescriptions. Eventually, Mencia did not even enter the room to see new
    Code-G patients.
    Mencia also instructed the assistants on how to write the charts to justify the
    prescriptions that he was signing for the new Code-G patients. He instructed them
    to note the level of a patient’s pain, not based on a consultation with the patient, but
    based on the level necessary to prescribe the drugs that Mencia had instructed them
    to give. Toward the end of this operation, Mencia would pre-sign blank prescriptions
    so that the medical assistants did not even have to bring them to him to sign. The
    government entered into evidence several text messages between Mencia and
    Ventura-Rodriguez that confirmed his testimony that Mencia had provided him with
    pre-signed prescriptions and had allowed him to write prescriptions before the date
    that another prescription was legally permitted.
    To help with his increasing patient load, Mencia contracted with a pain clinic
    in 2014 to hire Dr. Gabriel Marrero, a pain management specialist, to work one day
    per week at AGI. Marrero quickly became concerned that many of AGI’s patients
    were not interested in interventional pain, which was his specialty, and only cared
    about acquiring controlled substances. He also noticed that urine tests, MRIs, and x-
    rays were missing from patient files. He brought his concerns to Mencia’s attention,
    and Mencia agreed that these issues needed to be addressed. But Marrero continued
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    to see the same issues in patient files, which led him to discharge those patients.
    Unbeknownst to Marrero, Mencia would often take those patients back.
    Mencia took back one such patient after Marrero had discharged him for
    failing a urine test. That patient testified to having a drug addiction and to selling his
    prescriptions to buy more heroin. When he asked Mencia for larger quantities of the
    pills because his tolerance had increased, Mencia complied for all but one
    medication, saying that he had to “stay under the radar.”
    The beginning of the end for Mencia came when Dr. Abby Goldstein, a
    pharmacist at Publix Pharmacy, became concerned about the large number of
    oxycodone prescriptions that Code-G patients were bringing to the pharmacy. Dr.
    Goldstein informed the DEA about her concerns, telling them that Mencia “might
    be overprescribing certain medications,” including opioids. Dr. Goldstein testified
    that Mencia’s prescriptions stood out because “[n]inety-five percent of them were
    for a large quantity immediate-release narcotics,” particularly Percocet and
    oxycodone. Even though “a lot” of physicians were listed on the prescriptions from
    Mencia’s office, she only received prescriptions from Mencia. She was also
    concerned because, when she called AGI for the diagnosis codes for these
    prescriptions, she was told the same diagnosis for most patients. And when she
    looked Mencia up on the Board of Health license verification website, she
    discovered that he was not specially certified in pain management despite the large
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    number of pain medications that he was prescribing. Due to her growing concerns,
    Dr. Goldstein refused to fill approximately eighty percent of Mencia’s prescriptions
    for narcotics.
    Also as a result of Dr. Goldstein’s concerns, the government sent confidential
    informants into AGI to pretend that they were in pain and attempt to obtain
    controlled substance prescriptions. In the videos captured by those informants,
    medical assistants can be seen prescribing controlled substances on pre-signed
    prescription pads without Mencia ever entering the room or seeing the patients. The
    videos also show the patients paying in cash and sometimes “tipping” the assistants.
    The assistants would then pocket that cash. Ventura-Rodriguez testified, however,
    that he would later give that cash to someone else.
    Mencia was originally indicted along with three members of his office staff,
    Ventura-Rodriguez, Nadira Sampath-Grant, and John Mensah, for conspiracy to
    commit health care fraud and wire fraud and conspiracy to dispense controlled
    substances. Ventura-Rodriguez, Sampath-Grant, and Mensah each subsequently
    entered into plea agreements with the government and agreed to testify against
    Mencia. Mencia was then charged in a fifth superseding indictment with (1)
    conspiracy to commit health care fraud and wire fraud in violation of 
    18 U.S.C. § 1349
    ; (2) conspiracy to dispense oxycodone in violation of 
    21 U.S.C. § 846
    ; (3)
    dispensing oxycodone in violation of 
    21 U.S.C. § 841
    (a)(1); (4) seven counts of
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    money laundering in violation of 
    18 U.S.C. § 1957
    (a); and (5) structuring to avoid
    reporting requirements in violation of 
    31 U.S.C. § 5324
    (a)(3) and (d)(2).
    Mencia requested expert disclosures the day after he was indicted. One month
    later, and thirteen days before trial started, the government disclosed six experts,
    including Dr. Silverman. The government disclosed two additional experts the next
    day, including Dr. Jodi Sullivan. The defense filed a motion in limine to exclude the
    proposed expert testimony on the grounds that the government’s disclosures were
    untimely. The district court denied the motion.
    Dr. Silverman is a licensed physician and pain management specialist. He has
    published around nineteen articles in peer reviewed journals and a textbook on
    controlled substance management in chronic pain patients. The government
    presented Dr. Silverman as an expert on pain management and addiction “with the
    ability to opine on . . . the accepted scope of professional practice and whether
    medications are issued for a legitimate medical purpose.” Mencia objected on the
    grounds that (1) the term “scope of professional practice” does not appear in the
    statute under which Mencia was charged and (2) there had not been any testimony
    as to the methodology that Dr. Silverman used to reach his opinions. The court
    overruled his objection. Before testifying, Dr. Silverman reviewed Mencia’s
    prescribing history through the Florida Prescription Drug Monitoring Plan, several
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    videos that were taken at AGI by confidential government informants, and a selected
    number of patient notes.
    Based on his review of the evidence, Dr. Silverman opined that the controlled
    substances that Mencia prescribed in the period between 2014 and 2017 “did not
    have a medical legitimate need.” When asked whether there are Florida statutes that
    “act as guidance as to what is and is not acceptable practice,” Dr. Silverman replied
    that “[t]hey’re law. They’re not guidance.” And he determined that Mencia had
    violated those laws by failing to record proper medical examinations prior to
    prescribing controlled substances, develop a written treatment plan for assessing
    patients’ apparent drug-seeking behavior, or document an assessment of patients’
    risk related to that behavior or monitor the behavior on an ongoing basis. He also
    said that Mencia’s failure to refer patients whom he was treating for anxiety to
    psychiatrists violated the law. He was also concerned by the combination of
    medications that Mencia was prescribing due to the risk of fatal overdose. And he
    stated that it is both outside the scope of professional practice and outside Florida
    law for a physician to re-prescribe opioids after only a very brief check-in with the
    patient.
    Dr. Silverman also testified that it is illegal under Florida law for medical
    assistants to fill out prescriptions or make diagnoses or treatment plans. Their job,
    he stated, is to give the physician the facts so that the physician can conduct an
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    informed exam and come up with a plan. And he considered it to be outside the scope
    of professional practice for a medical assistant to see a patient, brief the doctor, and
    then for the doctor to sign a prescription for a controlled substance without seeing
    the patient himself.
    The defense asked Dr. Silverman whether there is criminal liability for
    violating Florida statutes regarding the standard of medical practice. First, the
    defense tried to ask Dr. Silverman to locate where the statutes provide for jail time.
    The government objected to that question as irrelevant, and the court sustained the
    objection. The defense then asked whether a certain statute is enforced by the Board
    of Medicine. Dr. Silverman responded that “it is my understanding that if you violate
    [Florida Statute §] 456.44, that––it was my understanding there were criminal
    penalties. I don’t know specifically what they were. But since they are law, I believe
    they (sic) were some penalties.” He then explained that “the enforcement of this I
    believe is through the DOH, Department of Health,” and “I don’t know if the patient
    goes before the Board of Medicine when you violate this. I believe this is a law. So,
    I think this is taken out of the administrative realm of the Board of Medicine. That’s
    my understanding.” The defense objected and moved to strike those comments as
    “an incorrect statement of law.”
    The court asked the government to stipulate that there are no criminal
    penalties in Section 456.44. The government stated that it was not aware of anything
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    in Section 456.44 stating that it carries criminal penalties. The defense then asked
    again whether a violation of Section 456.44 is brought before the Board of Medicine
    and emphasized that Dr. Silverman was brought before the Board of Medicine for a
    violation of that same statute for wrong-site injections.
    In its pretrial disclosures, the government stated that Dr. Sullivan, a licensed
    pharmacist, would testify regarding how Mencia’s unusual patterns of prescribing
    controlled substances were consistent with a “pill mill” based on her review of
    Mencia’s prescription data from the Florida Department of Health and Prescription
    Drug Event. Dr. Sullivan reviewed the Medicare Part D and Part B records for
    Mencia, a date-of-death analysis, and the Florida Prescription Drug Monitoring
    Program data for Mencia and 54 of his patients before testifying. The defense
    objected to Dr. Sullivan being tendered as an expert again at trial on the grounds that
    the government had not disclosed what methodology she used to reach her
    conclusions. The defense also requested a Daubert hearing. The court overruled the
    objection and stated that “she’s a qualified expert.”
    Dr. Carol Warfield testified for the defense. She teaches pain management at
    Harvard Medical School and elsewhere and has written textbooks on the subject.
    She was originally hired by the government but was dropped as a witness after
    opining that Mencia was acting as a medical doctor in the usual course of medical
    practice based on the medical records and videos that they asked her to review. She
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    also informed the government that she “had concerns” about the fact that he was
    signing blank prescriptions. The defense asked Dr. Warfield whether pre-signing
    blank prescriptions carries criminal penalties under Florida law, to which the
    government objected. The court sustained the objection.
    During cross-examination, the government asked Dr. Warfield about her
    concerns over the pre-signing of prescriptions. The prosecutor asked: “I believe what
    you told me was that under no circumstance would it be within the scope of
    professional practice to give a medical assistant a presigned prescription for them to
    fill out at their discretion for controlled two (sic) substances. Do you agree with
    that?” The defense objected and the court overruled, stating that “what the lawyers
    say isn’t evidence. The answers are evidence. If he wants to pursue this and waive
    his attorney-client –– waive his work product, he can do that.” Dr. Warfield
    answered that she “thought those medical assistants were practicing medicine
    without a license, and they in no way should have been given blank prescriptions to
    prescribe opiates to these patients.”
    The government referenced that testimony in closing. It stated that the core of
    the case was “about a doctor acting outside the scope of professional practice and
    not for a legitimate medical purpose when he provides medical assistants with
    presigned prescriptions.” The government then stated, “what you heard from both
    experts that on this matter, there is no dispute. It is outside the scope of professional
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    practice and not for a legitimate purpose to hand out presigned prescriptions for the
    medical assistants to fill in if the doctor has never seen the patient.” The government
    then reiterated, “[t]here’s no dispute about that.”
    The jury returned a guilty verdict only as to Count Two: conspiracy to
    dispense oxycodone unlawfully. Mencia timely appealed.
    II.    STANDARD OF REVIEW
    This Court reviews de novo whether sufficient evidence exists to support a
    guilty jury verdict, “reviewing the evidence in the light most favorable to the
    government and resolving all reasonable inferences and credibility evaluations in
    favor of the verdict.” United States v. Moran, 
    778 F.3d 942
    , 958 (11th Cir. 2015).
    We review the district court’s decision whether to admit expert testimony, and
    the district court’s assessment of the reliability of that testimony, for abuse of
    discretion and will only reverse the district court if its ruling was manifestly
    erroneous. United States v. Frazier, 
    387 F.3d 1244
    , 1258 (11th Cir. 2004) (en banc)
    (quoting Gen. Elec. Co. v. Joiner, 
    522 U.S. 136
    , 142 (1997)). We likewise review
    the district court’s decision whether to strike testimony for abuse of discretion. Mich.
    Millers Mut. Ins. Corp. v. Benfield, 
    140 F.3d 915
    , 920–21 (11th Cir. 1998).
    Accordingly, “we must affirm unless we find that the district court has made a clear
    error of judgment, or has applied the wrong legal standard.” Frazier, 
    387 F.3d at 1259
    .
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    Finally, we review a challenge to a statute’s constitutionality de novo. United
    States v. Knight, 
    490 F.3d 1268
    , 1270 (11th Cir. 2007).
    III.    DISCUSSION
    A. Sufficiency of the Evidence
    Mencia argues that there was insufficient evidence to support his conviction
    for conspiracy to violate Section 841(a). We disagree.
    The Controlled Substances Act makes it illegal for anyone to “knowingly or
    intentionally . . . . distribute . . . a controlled substance.” 
    21 U.S.C. § 841
    (a)(1). But
    there is an exception for licensed health care professionals––they may prescribe
    Schedule II, III, and IV controlled substances so long as the prescription is for a
    “legitimate medical purpose[] in the usual course of professional practice.” United
    States v. Joseph, 
    709 F.3d 1082
    , 1102 (11th Cir. 2013) (quoting United States v.
    Ignasiak, 
    667 F.3d 1217
    , 1228 (11th Cir. 2012)) ; United States v. Ruan, 
    966 F.3d 1101
    , 1122 (11th Cir. 2020). To convict a physician of violating Section 841(a)(1),
    the government must “prove that he dispensed controlled substances for other than
    legitimate medical purposes in the usual course of professional practice, and that he
    did so knowingly and intentionally.” Joseph, 709 F.3d at 1102 (quoting Ignasiak,
    667 F.3d at 1228). “Because the Act prohibits the distribution of prescription drugs
    that is not authorized, a distribution is unlawful if 1) the prescription was not for a
    ‘legitimate medical purpose’ or 2) the prescription was not made in the ‘usual course
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    of professional practice.’” Id. (cleaned up) (quoting United States v. Tobin, 
    676 F.3d 1264
    , 1282 (11th Cir. 2012), abrogated on other grounds by United States v. Davila,
    
    569 U.S. 597
    , 610 (2013)).
    Section 846 makes it illegal to conspire to violate Section 841(a)(1). See 
    21 U.S.C. § 846
    . To convict a defendant of violating Section 846, the government must
    prove that “(1) there was an agreement between two or more people to unlawfully
    distribute . . . controlled substances in violation of § 841(a)(1); (2) the defendant
    knew about the agreement; and (3) the defendant ‘voluntarily joined’ the
    agreement.” United States v. Iriele, 
    977 F.3d 1155
    , 1169 (11th Cir. 2020) (quoting
    United States v. Azmat, 
    805 F.3d 1018
    , 1035 (11th Cir. 2015)). The government may
    prove the first element, the existence of an agreement, “by proof of an understanding
    between the participants to engage in illicit conduct[.]” United States v. Achey, 
    943 F.3d 909
    , 916 (11th Cir. 2019). And the government may prove that understanding
    through circumstantial evidence. 
    Id.
    “[R]esolving all reasonable inferences and credibility evaluations in favor of
    the verdict,” Moran, 778 F.3d at 958, we conclude that sufficient evidence supports
    the jury’s verdict. Indeed, the evidence in this case is comparable to the evidence in
    in similar cases where we have affirmed guilty verdicts. Mencia set aside a class of
    patients known as “Code-G” patients and, even though he is a geriatric specialist,
    prescribed them the “holy trinity” of controlled substances for cash. Eventually, as
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    in Joseph, Mencia distributed these drugs by pre-signing and pre-dating
    prescriptions and instructing his medical assistants to give out those prescriptions.
    See Joseph, 709 F.3d at 1102. And he prescribed these controlled substances
    “without conducting any physical examination of the patient,” which “provides
    strong evidence to support a conviction under the Act.” Id. Moreover, Mencia
    continued to prescribe the “holy trinity” to various patients despite obvious signs of
    drug-seeking behavior that led Dr. Marrero to reject them. Ventura-Rodriguez
    testified that, as the number of Code-G patients increased, Mencia stopped entering
    the examination rooms at all––let alone physically examining the patients––before
    the medical assistants gave the patients prescriptions. And the video evidence
    gathered by confidential informants supports that testimony.
    This Court has found sufficient evidence that a physician distributed a
    prescription without a legitimate medical purpose and outside the usual course of
    professional conduct where, among other factors: “(1) An inordinately large quantity
    of controlled substances was prescribed[,] . . . (2) [l]arge numbers of prescriptions
    were issued[,]” (3) “[t]he physician prescribed controlled drugs at intervals
    inconsistent with legitimate medical treatment[,]” and (4) “[t]here was no logical
    relationship between the drugs prescribed and treatment of the condition allegedly
    existing.” United States v. Rosen, 
    582 F.2d 1032
    , 1036 (5th Cir. 1978). Here, Mencia
    regularly prescribed the maximum lawful dose of controlled substances and
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    combined them with high doses of other controlled substances. And he prescribed
    over 45,000 controlled substances in less than four years. He refilled at least one
    patient’s prescriptions early based on claims that the prescriptions had been stolen
    and authorized Ventura-Rodriguez to write prescriptions before the date that they
    were allowed. And several witnesses testified that there was no logical connection
    between the opioids that Mencia prescribed and the medical conditions that he was
    purporting to treat. Each of these pieces of evidence is “strong evidence to support
    a conviction under the Act.” Joseph, 709 F.3d at 1102.
    The government also provided sufficient evidence that an agreement existed
    between Mencia and his medical assistants to unlawfully distribute controlled
    substances. An “agreement may be inferred when the evidence shows a continuing
    relationship that results in the repeated transfer of illegal drugs to the purchaser.”
    United States v. Mercer, 
    165 F.3d 1331
    , 1335 (11th Cir. 1999). Here, Mencia’s
    medical assistants testified at length about the understanding between them and
    Mencia that they could fill in pre-signed prescriptions for controlled substances
    without a physician ever examining the patients. Mencia instructed the assistants to
    fill in patient charts, not based on a patient’s actual data, but based on the “data that
    would justify the reason why the patient would be prescribed the drugs.” And the
    medical assistants did so. Through this testimony, the government demonstrated that
    Mencia and his medical assistants had an agreement that he would instruct them on
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    what controlled substances to prescribe, for no legitimate medical reason and outside
    the usual course of professional practice, and that they would unlawfully write those
    prescriptions in exchange for patients’ cash payments. Accordingly, there was
    sufficient evidence to support Mencia’s conviction.
    B. Expert Witnesses
    Mencia next argues that the district court abused its discretion in allowing
    certain expert testimony. He challenges the district court’s resolution of in-trial
    objections to specific portions of Dr. Silverman’s and Dr. Warfield’s testimony.
    And he argues that neither Dr. Silverman nor Dr. Sullivan should have been allowed
    to testify as experts at all.
    1. In-trial Objections to Expert Testimony
    First, Mencia argues that the district court abused its discretion in allowing
    Dr. Silverman to testify that, in his opinion, Mencia acted outside the scope of
    professional practice in treating certain patients. We disagree. An expert witness
    may testify about an opinion that “embraces an ultimate issue,” Fed. R. Evid. 704(a),
    but may not “merely tell the jury what result to reach” or “testify to the legal
    implications of conduct[.]” Montgomery v. Aetna Cas. & Sur. Co., 
    898 F.2d 1537
    ,
    1541 (11th Cir. 1990). “In a criminal case, an expert witness must not state an
    opinion about whether the defendant did or did not have a mental state or condition
    that constitutes an element of the crime charged or of a defense.” Fed. R. Evid.
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    704(b). In other words, “the expert cannot expressly state a conclusion that the
    defendant did or did not have the requisite intent,” United States v. Alvarez, 
    837 F.2d 1024
    , 1031 (11th Cir. 1988), but he can provide an opinion as to facts that support
    such a conclusion, United States v. Augustin, 
    661 F.3d 1105
    , 1123 (11th Cir. 2011).
    Dr. Silverman opined that the controlled substances that Mencia prescribed to
    certain patients “did not have a medical legitimate need.” And he stated that Florida
    law defines what is and is not within the scope of professional practice for physicians
    licensed in the state. Based on those laws, he opined that Mencia was acting outside
    the scope of professional practice when he failed to (1) record proper medical
    examinations prior to prescribing controlled substances, (2) develop a written
    treatment plan for assessing patients’ apparent drug-seeking behavior, or (3)
    document an assessment of patients’ risk related to that behavior or monitor the
    behavior on an ongoing basis. He further testified that allowing medical assistants
    to fill out prescriptions or make diagnoses or treatment plans violates Florida law.
    The district court did not abuse its discretion in admitting this testimony. To
    prove that Mencia was guilty of conspiracy to unlawfully distribute controlled
    substances, the government had to prove that he knowingly and intentionally
    dispensed those substances for other than legitimate medical purposes in the usual
    course of professional practice. See Joseph, 709 F.3d at 1094. But Dr. Silverman did
    not testify that Mencia knowingly and intentionally acted outside the usual course
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    of professional practice. Instead, he testified that, in his opinion, because Mencia’s
    actions violated Florida law, Mencia was acting outside the usual course of
    professional practice. Whether Mencia knew that he was doing so or intended to do
    so is another question.
    That intent question, whether a physician knowingly and intentionally
    prescribed a medication for other than a legitimate medical purpose outside the usual
    course of professional practice, is for the jury. See United States v. Guerrero, 
    650 F.2d 728
    , 734 (5th Cir. 1981 Unit A). But what practices fall within the usual course
    of professional practice is precisely what an expert witness is needed to define.
    Based on that definition and Dr. Silverman’s opinions, the jury was free to infer
    whether or not Mencia knew he was acting or intended to act outside of the usual
    course of professional practice or whether he knew he was prescribing or intended
    to prescribe medications without a legitimate medical purpose. See United States v.
    Greenfield, 
    554 F.2d 179
    , 184–86 (5th Cir. 1977). Because Dr. Silverman did not
    state that Mencia had the requisite intent to commit the crime alleged, but instead
    offered his opinion that Mencia was acting outside the usual course of professional
    practice and without a legitimate medical justification, the district court did not err
    in allowing his testimony.
    Second, Mencia argues that the district court abused its discretion in declining
    to strike Dr. Silverman’s statement during cross-examination that violating Section
    20
    USCA11 Case: 18-13967       Date Filed: 06/09/2021    Page: 21 of 33
    456.44 carries criminal penalties. We disagree. When defense counsel asked “where
    the statute provides for a criminal penalty, any sort of jail time,” the district court
    sustained the government’s objection on relevance grounds. When defense counsel
    continued and asked whether the statute is “enforced by the Board of Medicine,” Dr.
    Silverman responded that “it was my understanding there were criminal penalties. I
    don’t know specifically what they were.” The defense then objected to Dr.
    Silverman’s answer and moved to strike because it was “an incorrect statement of
    the law.” Instead of sustaining the objection, the court asked the government to
    stipulate that there are no criminal penalties and the government responded that it
    was not aware of anything in Section 456.44 that defines a violation as a
    misdemeanor, felony, or anything else.
    The district court did not err in resolving Mencia’s objection to his own
    question. Although the government argues that the invited error doctrine prevents
    Mencia from raising this issue on appeal, see United States v. Sarras, 
    575 F.3d 1191
    ,
    1216 (11th Cir. 2009), we need not decide that point here. Even if the district court
    erred by declining to strike this allegedly erroneous portion of Dr. Silverman’s
    testimony, that error was harmless. See United States v. Frediani, 
    790 F.3d 1196
    ,
    1202 (11th Cir. 2015). Under the harmless error standard, we need not reverse a
    conviction because of evidentiary error when “the error had no substantial influence
    21
    USCA11 Case: 18-13967       Date Filed: 06/09/2021   Page: 22 of 33
    on the outcome and sufficient evidence uninfected by error supports the verdict.” 
    Id.
    (quoting United States v. Hands, 
    184 F.3d 1322
    , 1329 (11th Cir. 1999)).
    That is the case here. To convict Mencia under Section 846, the government
    needed to prove that Mencia conspired to distribute a controlled substance in
    violation of Section 841(a)(1)—that is, for “other than legitimate medical purposes”
    or outside “the usual course of professional practice.” Joseph, 709 F.3d at 1102
    (quoting Ignasiak, 667 F.3d at 1228). To do so, the government called Dr. Silverman
    to testify. Although Dr. Silverman testified that he believed a state law defining the
    standard of medical practice carried criminal penalties, the existence of criminal
    penalties under that law is immaterial to whether Mencia’s actions comport with the
    standard that law sets. On top of that, Dr. Silverman’s testimony was not necessary
    to establish whether Mencia’s actions were consistent with “accepted standards of
    professional practice”—lay testimony and other evidence work just as well. See id.
    at 1103. And on that front, the government introduced overwhelming evidence that
    Mencia conspired to distribute controlled substances for “other than legitimate
    medical purposes” or outside “the usual course of professional practice.” Id. at 1102
    (quoting Ignasiak, 667 F.3d at 1228). For example, several witnesses testified that
    there was no logical connection between the medical conditions Mencia treated and
    the opioids he prescribed; three of Mencia’s co-conspirators testified at length that
    he instructed them to sell medically unnecessary, pre-signed prescriptions for cash;
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    USCA11 Case: 18-13967        Date Filed: 06/09/2021     Page: 23 of 33
    Marrero testified that many of Mencia’s patients displayed obvious signs of drug-
    seeking behavior and that their patient files were incomplete, often missing standard
    urine tests, MRIs, and x-rays; and the government introduced undercover DEA
    recordings in which Mencia prescribed controlled substances without conducting
    physical examinations of patients. Taken together, any error in failing to strike the
    allegedly erroneous portion of Dr. Silverman’s testimony was harmless; it “had no
    substantial influence on the outcome and sufficient evidence uninfected by error
    supports the verdict.” Frediani, 790 F.3d at 1202 (quoting Hands, 
    184 F.3d at 1329
    ).
    Third, Mencia argues that the government improperly implied the existence
    of additional evidence not before the jury by asking Dr. Warfield about a previous
    inconsistent statement. Again, we disagree. Specifically, the prosecutor asked: “I
    believe what you told me was that under no circumstance would it be within the
    scope of professional practice to give a medical assistant with a presigned
    prescription for them to fill out at their discretion for controlled two (sic) substances.
    Do you agree with that?” “It is hornbook law that evidence of prior inconsistent
    statements of a witness may be admitted to impeach that witness.” United States v.
    Sisto, 
    534 F.2d 616
    , 622 (5th Cir. 1976). “The prior statements may have been oral
    and unsworn, and the making of the previous statements may be drawn out in cross-
    examination of the witness himself.” 
    Id.
     (quotation marks and citation omitted). For
    her part, Dr. Warfield had an opportunity to answer––she responded that she had
    23
    USCA11 Case: 18-13967       Date Filed: 06/09/2021   Page: 24 of 33
    said only that she “thought those medical assistants were practicing medicine
    without a license, and they in no way should have been given blank prescriptions to
    prescribe opiates to these patients.” And the court correctly instructed the jury in
    response to Mencia’s objection to this question that “what the lawyers say isn’t
    evidence. The answers are evidence.” The district court did not abuse its discretion
    in ruling on Mencia’s objection.
    2. Dr. Silverman’s and Dr. Sullivan’s Methodologies, Qualifications, and
    Disclosures
    Mencia next argues that the court abused its discretion in allowing Drs.
    Silverman and Sullivan to testify as experts because (1) the court should have
    conducted Daubert hearings before qualifying them as experts, and Dr. Silverman’s
    methodology was not sufficiently reliable; and (2) Dr. Silverman’s disclosures were
    insufficient, and the untimeliness of the government’s disclosures prejudiced the
    defense. We address each argument in turn.
    First, the district court did not abuse its discretion in declining to conduct
    Daubert hearings. In Daubert v. Merrell Dow Pharmaceuticals, Inc., and its
    progeny, the Supreme Court explained the requirements for expert testimony to be
    admissible under Federal Rule of Evidence 702. 
    509 U.S. 579
    , 589–94 (1993). Such
    testimony is admissible if the expert is qualified, the expert’s methodology is
    reliable, and the testimony assists the trier of fact. City of Tuscaloosa v. Harcros
    Chems., Inc., 
    158 F.3d 548
    , 562 (11th Cir. 1998) (citation omitted). When assessing
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    USCA11 Case: 18-13967       Date Filed: 06/09/2021    Page: 25 of 33
    methodology, courts should consider, where applicable, “whether it can be (and has
    been) tested,” “whether the theory or technique has been subjected to peer review
    and publication,” “the known or potential rate of error, . . . and the existence and
    maintenance of standards controlling the technique’s operation,” and “general
    acceptance.” Daubert, 
    509 U.S. at
    593–94 (citation omitted). But that inquiry is “a
    flexible one.” 
    Id. at 594
    . If an expert’s methodology is based “solely or primarily on
    experience, then the witness must explain how that experience leads to the
    conclusion reached, why that experience is a sufficient basis for the opinion, and
    how that experience is reliably applied to the facts.” Fed. R. Evid. 702 advisory
    committee’s note to 2000 amends.
    In Azmat, we held that the district court did not abuse its discretion in allowing
    expert testimony where the government detailed the “federal and state medical
    guidelines, literature from national organizations, published journal articles, and
    [medical] textbooks” that the expert relied on in reaching his conclusions. 805 F.3d
    at 1042. The government had also explained the expert’s “method of reviewing
    patient files, which involved [the expert] weighing [the defendant’s] decisions
    against the standards articulated in the” medical texts that the expert relied on and
    the expert “exercising his judgment as an experienced medical practitioner to reach
    conclusions” as to the defendant’s conduct. Id. Because the expert “relied on
    published sources generally accepted by the medical community in defining the
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    USCA11 Case: 18-13967         Date Filed: 06/09/2021     Page: 26 of 33
    applicable standard of care,” the district court did not abuse its discretion in
    admitting the testimony. Id.
    To determine whether an expert’s methodology meets Daubert’s standards, a
    district court can, but is not required to, conduct a Daubert hearing. See City of
    Tuscaloosa, 158 F.3d at 564 n.21. Daubert hearings are particularly helpful “in
    complicated cases involving multiple expert witnesses[.]” Id. “A district court
    should conduct a Daubert inquiry when the opposing party’s motion for a hearing is
    supported by ‘conflicting medical literature and expert testimony.’” United States v.
    Hansen, 
    262 F.3d 1217
    , 1234 (11th Cir. 2001) (quoting Tanner v. Westbrook, 
    174 F.3d 542
    , 546 (5th Cir. 1999)).
    Here, Dr. Silverman’s experience includes a medical degree, board
    certifications in pain management and addiction, more than twenty years of pain
    management in Florida, authorship of numerous peer-reviewed articles and a
    textbook on pain management, and a history of assisting state and federal
    investigations into the opioid crisis in Florida. He testified that his practice, training,
    experience, and education have made him familiar with the “accepted scope of
    professional practice when it comes to pain management and opioid prescriptions.”
    Based on those qualifications, the government tendered him as an expert in pain
    management and addiction “with the ability to opine on what is and what is not, in
    26
    USCA11 Case: 18-13967       Date Filed: 06/09/2021    Page: 27 of 33
    his opinion, within the accepted scope of professional practice and whether
    medications are issued for a legitimate medical purpose.”
    Dr. Silverman applied that experience to the evidence to form his opinions.
    He reviewed patient files that the government selected for him, a list of the controlled
    substances that were prescribed to Dr. Mencia’s patients, applicable Florida statutes,
    applicable federal regulations, and the confidential informant videos and transcripts.
    He then applied his experience and knowledge to that data to determine that Mencia
    was acting outside the scope of professional practice in prescribing certain controlled
    substances without a legitimate medical purpose.
    The district court did not abuse its discretion in admitting that testimony. The
    district court was required to assess Dr. Silverman’s methodology before admitting
    his testimony and the government provided ample evidence of his qualifications and
    the resources that he relied on in coming to his opinions. Like in Azmat, those
    resources included applicable law and “published sources generally accepted by the
    medical community in defining the applicable standard of care.” 805 F.3d at 1042.
    The court was not required to conduct a Daubert hearing, and the defense did
    not support its objection with conflicting medical literature or expert testimony. See
    Hansen, 
    262 F.3d at 1234
    . Mencia argues that Dr. Warfield’s conflicting opinions
    should have necessitated a Daubert hearing, but he did not make that argument in
    his motion to exclude Dr. Silverman’s expert testimony or in his objection. Instead,
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    he merely argued that Dr. Silverman’s methodology was insufficiently reliable.
    Under such a deferential standard of review, that is insufficient reasoning for this
    Court to reverse the district court’s decision. Because the district court’s decision
    not to hold a Daubert hearing was based on the implicit decision that Dr. Silverman’s
    methodology was reliable, the district court did not abuse its discretion in making
    that determination, either.
    Second, the district court did not abuse its discretion in overruling Mencia’s
    objection to the government’s pre-trial disclosures as incomplete or untimely. At the
    defendant’s request, the government must give a defendant a written summary of
    any expert testimony it intends to use, which “must describe the witness’s opinions,
    the bases and reasons for those opinions, and the witness’s qualifications.” Fed. R.
    Crim. P. 16(a)(1)(G). In the absence of a scheduling order, this Court has not stated
    a bright-line rule for how far in advance of trial the government should provide a
    summary. But this Court has held that a summary provided “almost one month
    before trial” was sufficient, even when the identity of the proposed expert changed
    weeks later. See United States v. Chalker, 
    966 F.3d 1177
    , 1193 (11th Cir. 2020). In
    any event, this Court “will not reverse a conviction based on a Rule 16 expert
    disclosure violation unless the violation prejudiced the defendant’s substantial
    rights.” 
    Id.
     (quoting United States v. Stahlman, 
    934 F.3d 1199
    , 1222 n.10 (11th Cir.
    2019)). A defendant must establish that the violation of Rule 16 “adversely affected
    28
    USCA11 Case: 18-13967      Date Filed: 06/09/2021   Page: 29 of 33
    their ability to present a defense.” United States v. Chastain, 
    198 F.3d 1338
    , 1348
    (11th Cir. 1999).
    There is no reversible error in this case. The government disclosed Drs.
    Silverman and Sullivan about one month after Mencia requested its disclosures,
    thirteen and twelve days before trial, respectively. Even assuming for the sake of
    argument that those disclosures came too close to trial, we cannot say the timing
    adversely affected Mencia’s ability to present a defense. The government agreed to
    a trial continuance to allow Mencia more time to prepare, but he did not ask for one.
    See United States v. Rivera, 
    944 F.2d 1563
    , 1566 (11th Cir. 1991) (“if Rivera had,
    in fact, been prejudiced by the delayed disclosure . . . he should have moved for a
    continuance”). And Mencia presented a rebuttal expert witness, Dr. Warfield, whose
    opinions directly conflicted with Dr. Silverman’s opinions. He also had time to
    acquire Dr. Silverman’s Florida Department of Health disciplinary records to use
    during cross-examination.
    The disclosures were also sufficient. In its disclosures, the government
    summarized Dr. Silverman’s testimony as opining “that the defendant prescribed or
    caused to be prescribed Schedule II substances outside the course of professional
    practice and not for a legitimate medical purpose.” He would additionally opine on
    Mencia’s conduct in the undercover recordings, concluding that the conduct was
    “outside the scope of professional practice.” Mencia argues that this description did
    29
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    not encompass Dr. Silverman’s testimony that Mencia’s conduct in pre-signing
    prescriptions and allowing medical assistants to see patients alone before merely
    signing a prescription fell outside the scope of professional practice. But those
    opinions were encompassed by the government’s summary. Whether Mencia
    prescribed or caused to be prescribed controlled substances outside the course of
    professional practice encompasses pre-signing prescriptions and signing them
    without seeing patients. And the undercover recordings included medical assistants
    seeing patients alone and giving them prescriptions without consulting with Mencia.
    But even if the government’s summary was too vague, it again did not impair
    Mencia’s substantial rights because he was able to present Dr. Warfield’s conflicting
    testimony on the same issues.1
    C. Constitutionality
    Finally,    Mencia       argues    that    the    Controlled      Substances      Act     is
    unconstitutionally vague as applied to physicians. He contends that, because no
    statute or regulation defines the standard of care against which his conduct can be
    compared, that standard was defined by “unqualified government experts” and
    Mencia was convicted “based on this nebulous definition of standard of care.”
    1
    Mencia argues for the first time on appeal that Dr. Sullivan was not qualified to testify as an
    expert. Mencia did not object to Dr. Sullivan’s testimony on that ground––the defense argued only
    that her methodology had not been sufficiently vetted by the district court. Accordingly, we review
    that argument for plain error, Fed. R. Crim. P. 52(b), and conclude that the district court did not
    plainly err in allowing Dr. Sullivan’s testimony.
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    When “a vagueness challenge does not involve the First Amendment, the
    analysis must be as applied to the facts of the case.” United States v. Wayerski, 
    624 F.3d 1342
    , 1347 (11th Cir. 2010). Mencia has not raised a First Amendment
    challenge. Accordingly, the question for this Court is whether the Act “fails to
    provide people of ordinary intelligence a reasonable opportunity to understand what
    conduct it prohibits’ or ‘it authorizes or even encourages arbitrary and
    discriminatory enforcement.’” 
    Id.
     (quoting Hill v. Colorado, 
    530 U.S. 703
    , 732
    (2000)). To establish that the Act is unconstitutionally vague, Mencia must
    overcome the “strong presumption that statutes passed by Congress are valid.” 
    Id.
    In United States v. Collier, a physician appealed his conviction under Section
    841(a)(1) for distribution of methadone while acting outside the usual course of
    professional practice. 
    478 F.2d 268
    , 270 (5th Cir. 1973). This Court rejected the
    physician’s argument that the phrase “in the course of his professional practice” did
    not give physicians notice as to what conduct violates the statute. 
    Id.
     at 270–72. We
    held that the statute necessarily gave physicians “a certain latitude of available
    options,” because “the physician must make a professional judgment as to whether
    a patient’s condition is such that a certain drug should be prescribed.” 
    Id. at 272
    .
    And that judgment is what physicians must routinely exercise in prescribing
    controlled substances. 
    Id.
     Accordingly, the Act’s prohibition of distributing
    controlled substances outside the course of professional practice is not
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    unconstitutionally vague; it is a clear reference to the judgment calls that physicians
    routinely make. 
    Id.
    Here, Mencia makes an argument nearly identical to the defendant’s argument
    in Collier. He argues that the lack of a statute or regulation defining the baseline
    standard of care renders the Act unconstitutionally vague as applied to physicians.
    But this Court already held that the phrase “in the course of his professional practice”
    is not unconstitutionally vague and does not require a statutory or regulatory
    definition because it is a necessarily fact-intensive inquiry in which physicians must
    exercise their professional judgment. 
    Id.
     And Mencia fails to distinguish his
    argument from the defendant’s argument in Collier. Instead, he argues that his case
    is different because he was not acting as a drug pusher. But that is exactly the
    question that the Act seeks to answer––when does a physician stop acting as a doctor
    and start acting as a “drug pusher.” The answer under the Act is when he prescribes
    controlled substances outside the course of his professional practice or without a
    legitimate medical purpose. Because this Court has already rejected the exact
    argument that Mencia raises, we affirm.
    IV.    CONCLUSION
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    The government provided sufficient evidence of Mencia’s guilt, the district
    court properly admitted the expert testimony, and the Act is not unconstitutionally
    vague as applied to physicians. Accordingly, we affirm.
    33