City of Des Moines v. Iowa Dep't of Transp. & Iowa Transp. Comm'n ( 2018 )


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  •                IN THE SUPREME COURT OF IOWA
    No. 17–0686
    Filed April 27, 2018
    CITY OF DES MOINES, IOWA,
    CITY OF MUSCATINE, IOWA,
    and
    CITY OF CEDAR RAPIDS, IOWA,
    Appellants,
    vs.
    IOWA DEPARTMENT OF TRANSPORTATION
    and IOWA TRANSPORTATION COMMISSION,
    Appellees.
    Appeal from the Iowa District Court for Polk County, Scott D.
    Rosenberg, Judge.
    Three cities appeal a district court order upholding administrative
    rules issued by the Iowa Department of Transportation. REVERSED AND
    REMANDED.
    Michelle R. Mackel-Wiederanders and Carol J. Moser, Des Moines,
    Douglas A. Fulton, Matthew S. Brick, and Erin M. Clanton of Brick Gentry,
    P.C., West Des Moines, Elizabeth D. Jacobi and James H. Flitz, Cedar
    Rapids, for appellants.
    2
    Thomas J. Miller, Attorney General, David S. Gorham, Special
    Assistant Attorney General, and Richard E. Mull, Assistant Attorney
    General, for appellees.
    3
    MANSFIELD, Justice.
    We must determine whether the Iowa Department of Transportation
    (IDOT) had the statutory authority to promulgate administrative rules
    regulating automated traffic enforcement (ATE) systems located along
    primary roads.     See Iowa Admin. Code ch. 761—144 (2014).               The
    enforcement of these rules resulted in three cities being ordered to relocate
    or remove several of their ATE cameras.
    The issue presented is the reach of the administrative state: Before
    the executive branch can adopt a rule with the force and effect of law, how
    much groundwork must be laid by the legislative branch? After all, article
    III, section 1 states that “[t]he legislative authority of this state shall be
    vested in a general assembly . . .”—not the executive branch. Iowa Const.
    art. III, § 1. Article III, section 1 also states that “no person charged with
    the exercise of powers properly belonging to one of these departments shall
    exercise any function appertaining to either of the others, except in cases
    hereinafter expressly directed or permitted.” Id.
    On our review, we find that the IDOT did not have authority from
    the legislature to issue rules regulating ATE systems. The IDOT’s specific
    grants of authority are in other areas and do not support the rules.
    Moreover, any general authority over “regulation and improvement of
    transportation” is too broad to sustain the rules—particularly in light of
    the specific grants of authority in other areas. See 
    Iowa Code § 307.2
    (2013).   Accordingly, we conclude the rules are invalid and cannot be
    enforced against the cities.   Therefore, we reverse the judgment of the
    district court and remand for further proceedings.
    I. Facts and Procedural Background.
    This dispute is between the IDOT and three cities—Cedar Rapids,
    Des Moines, and Muscatine (the Cities). The Cities have installed ATE
    4
    systems on primary roads within their boundaries. 1 The IDOT has sought
    to regulate and limit those ATE systems through administrative rules.
    A. The Installation of the Cities’ ATE Systems. Until 2014, the
    IDOT had no formal rules governing ATE systems but instead relied on
    informal guidelines.        In 2010, working within these guidelines, Cedar
    Rapids obtained the IDOT’s written agreement that the city could install
    ATE equipment. Cedar Rapids placed these systems in various locations
    within its city limits. These places included Interstate 380 and 1st Avenue
    East at the intersection of 10th Street. Both I-380 and 1st Avenue East
    are considered primary roads.
    Early in 2011, Muscatine also obtained the IDOT’s written
    agreement to install ATE equipment within its limits, following a study of
    accident data and speeding and red-light surveys. The locations included
    two intersections along Highway 61, a primary road.
    Later that year, Des Moines also received IDOT’s agreement that it
    could install ATE cameras to monitor red-light running and speeding.
    These included an ATE system to detect speeding vehicles traveling
    eastbound on Interstate 235, between 42nd Street and Polk Boulevard. I-
    235 is also a primary road. The specific location on I-235 was chosen
    because of traffic flow, highway grade, and layout, which the city
    maintained made it more difficult for officers to monitor speed safely from
    their patrol cars.
    1ATE   systems use automated cameras to record motorists who commit traffic
    violations, such as speeding or running a red light. After the vehicle and its license
    number have been photographed, a citation is sent to the registered owner of the vehicle.
    See, e.g., Des Moines, Iowa, Code of Ordinances § 114-243 (2018). Typically, only a fine
    is charged. See, e.g., id. There is no effect on the motorist’s driving or insurance record,
    and it is only a civil infraction. Also, the ATE systems generally result in a speeding
    citation only when the motorist is driving a certain threshold amount above the speed
    limit—such as more than ten miles per hour above the limit. See, e.g., Muscatine, Iowa,
    City Code § 7-5-5 (2018).
    5
    IDOT’s standard agreements—which each of the Cities executed—
    stated that the agency reserved the right to “[r]equire the removal of such
    traffic control device upon thirty days’ written notice.    Either lack of
    supervision,   inadequate    enforcement,    unapproved    operation,   or
    intolerable congestion shall be considered sufficient reason to require
    removal.”
    B. The IDOT’s Rulemaking.        On October 2, 2013, the IDOT
    commenced a rulemaking proceeding to regulate and restrict ATE
    placement and usage on primary roadways. See Iowa Code § 17A.4. In
    accordance with requirements of the Iowa Administrative Procedures Act,
    the IDOT published proposed rules and accepted written comments on
    them. See id. § 17A.4(1)(a)–(b).
    Among other things, the proposed rules provided that ATE systems
    “shall only be considered after other engineering and enforcement
    solutions have been explored and implemented,” “should not be used as a
    long-term solution for speeding or red-light running,” and “should only be
    considered in extremely limited situations on interstate roads because
    they are the safest class of any roadway in the state and they typically
    carry a significant amount of non-familiar motorists.” Notice of Intended
    Action, Admin. Rules Review Comm. 1037C (IDOT Oct. 2, 2013),
    https://www.legis.iowa.gov/docs/aco/arc/1037C.pdf.         The   proposed
    rules also required advance approval by the IDOT and a detailed
    “justification report” for any ATE system. Thereafter, localities would be
    required to submit detailed annual evaluations to assist the IDOT in
    reevaluating each ATE system and deciding whether to allow its continued
    use.
    6
    Many comments were submitted expressing sharply divergent
    viewpoints. 2    Most commenters did not discuss the actual rules but
    addressed the pros and cons of ATE systems generally. For example:
    “I strongly support the use of traffic cameras in Cedar
    Rapids—specifically on I380. They are working!”
    “In general, I am against the indiscriminate use of ‘spy
    cameras’ as a means to collect massive fines from drivers.”
    “I like the idea of traffic cameras for speeding and red
    lights. I believe they do help to sa[v]e lives.”
    “I am in total agreement of getting rid of photo enforced
    speed cameras in Iowa. It is an invasion of privacy. Thank
    you for using common sense on this issue.”
    “I welcome fewer restrictions on the installation of
    speed and red-light cameras. It’s the easiest way to keep
    drivers honest and legal. And that’s good for everyone.”
    “I am totally against traffic cameras and think they
    should be outlawed.”
    “Anything to get people to obey traffic laws is a good
    thing, even if it is unpopular. Calling the cameras distracting
    to drivers just to get rid of them is a cheap shot. KEEP THE
    CAMERAS.”
    “I see ABSOLUTELY NO value in traffic cameras placed
    on the highway.”
    Some commenters offered more specific suggestions.                One
    commenter urged that
    [s]peed cameras should not be placed where there is a sudden
    reduction in the speed limit. It is dangerous to have a speed
    sign reducing speed a short distance from the camera. The
    locals know to reduce their speed and start slamming on [their
    brakes], which is not safe for traffic.
    Along the same lines, another commenter recommended “that the
    Department additionally restrict ATEs’ placement in locations where a
    higher speed zone is transitioning to a lower speed zone.” Yet another
    2The   IDOT received a total of 164 written comments.
    7
    commenter proposed that ATE systems “[n]ot be placed within 1,000 feet
    of either side of a posted speed limit sign.”
    On October 30, the IDOT held a public hearing to afford interested
    persons an opportunity to speak out on the proposed rules.           At the
    hearing, representatives of the Cities, in addition to other officials and
    members of the public, made oral presentations.         A total of thirteen
    persons spoke.
    Again, the subject of limiting the use of speed cameras within a
    certain distance of new speed limits came up. For example, one speaker
    expressed concerns about municipalities installing ATE systems “in areas
    where the speed is going from a faster speed zone to a slower speed zone .
    . . because those are areas where more people are likely to slam on their
    brakes, and it would be . . . more dangerous.”
    The IDOT held a subsequent meeting on December 10 to present the
    final rules and detail the feedback it had received throughout the process.
    At this time, the IDOT unveiled modifications to the rules. These included
    a “1000-foot rule”—i.e., that ATE equipment could not be stationed within
    1000 feet of a speed limit change.          The IDOT explained that this
    modification was in response to prior comments.
    In most other respects, the final rules mirrored the initial rules the
    IDOT had proposed in October. Thus, all ATE locations on the primary
    road system had to be approved by the IDOT. 
    Iowa Admin. Code r. 761
    —
    144.4(3).   The final rules contained a requirement that any “local
    jurisdiction requesting to use an automated traffic enforcement system on
    the primary road shall provide the department a justification report.” 
    Id.
    r. 761—144.5(1). Such report needed to include documentation as to “why
    the area is a high-crash or high-risk location.” 
    Id.
     r. 761—144.5(1)(a).
    According to the rules, ATE systems “should only be considered in
    8
    extremely limited situations on interstate roads because they are the safest
    class of any roadway in the state and they typically carry a significant
    amount of non-familiar motorists.” 
    Id.
     r. 761—144.4(1)(c). After the ATE
    equipment was installed, the rules required “each local jurisdiction with
    active automated enforcement on Iowa’s primary highway system [to]
    evaluate the effectiveness of its use” on an ongoing basis. 
    Id.
     r. 761—
    144.7(1). The annual evaluation must
    (1) Address the impact of automated enforcement
    technology on reducing speeds or the number of red-light
    running violations for those sites being monitored.
    (2) Identify the number and type of collisions at the sites
    being monitored, listing comparison data for before-and-after
    years. If the system includes intersection enforcement, only
    the monitored approaches should be included in the
    evaluation.
    (3) Evaluate and document the automated traffic
    enforcement system’s impact on addressing the critical traffic
    safety issue(s) listed in the justification report if a justification
    report was part of the system’s initial approval process.
    (4) Provide the total number of citations issued for each
    calendar year the system has been in operation.
    (5) Certify that the calibration requirements of subrule
    144.6(4) have been met.
    
    Id.
     r. 761—144.7(1)(a).
    The IDOT would determine whether use of the ATE system would
    continue. 
    Id.
     r. 761—144.8. “Continued use [would] be contingent on the
    effectiveness of the system, appropriate administration of it by the local
    jurisdiction, the continued compliance with these rules, changes in traffic
    patterns, infrastructure improvements, and implementation of other
    identified safety countermeasures.” 
    Id.
     r. 761—144.8(1). Additionally, the
    department explicitly “reserve[d] the right to require removal or
    9
    modification of a system in a particular location, as deemed appropriate.”
    
    Id.
     r. 761—144.8(2). The rules became effective February 12, 2014.
    C. The IDOT’s Subsequent Directives to Remove Certain ATE
    Systems. Once the ATE rules became effective, each city submitted an
    evaluation to the IDOT in an effort to justify the continued presence of the
    cameras. Cedar Rapids provided crash data showing that crashes at 1st
    Avenue and 10th Street had remained roughly constant since the
    installation of the ATE systems.     However, on I-380 there had been
    declines both in overall crashes and, especially, personal injury crashes.
    Whereas one fatal crash had occurred in 2008 and two in 2009, no fatal
    crashes had occurred in the relevant area of I-380 since the ATE cameras
    were installed.
    Muscatine reported that totaling the five intersections where ATE
    equipment had been installed, crashes had declined significantly overall.
    In 2010, there had been thirty-four motor vehicle crashes including nine
    injury crashes; by contrast, during the year 2013, there had been nineteen
    crashes, of which four were injury crashes.
    Des Moines’s report also argued that its ATE systems had had a
    positive safety impact. Regarding the I-235 location, the report concluded
    that “the total number of accidents on I-235 in this area (4700 block to
    4200 block) have decreased since the implementation of our camera
    program.”
    Nonetheless, the IDOT ordered all of the Cities to disable or move
    some of their ATE equipment. Cedar Rapids was told to disable its ATE
    speed detection system at the intersection of 1st Avenue and 10th Street
    because it violated the 1000-foot rule. The IDOT also told Cedar Rapids
    to move, remove, or disable its ATE cameras on I-380 either because of the
    1000-foot rule or because “[t]he location of the camera is well beyond the
    10
    ‘S’ curve [on I-380] and therefore beyond the area of concern.” The IDOT
    further cited Iowa Administrative Code rule 761—144.4(1)(c) regarding the
    limited use of ATE systems on interstate roadways.
    Muscatine was ordered to remove its ATE camera from Highway 61
    at University because it violated the 1000-foot rule, because there were a
    high number of citations, and because crashes had increased at this
    particular location since the camera was installed.
    The IDOT directed Des Moines to remove its ATE camera from I-235
    as well. Although it acknowledged a reduction in crashes since the camera
    was activated, it pointed to its own rule that ATE should only be considered
    in extremely limited situations on interstate highways and observed that
    “[t]his location experiences a low crash rate.”    It also noted the high
    number of citations.
    Each city appealed, and the department director upheld each
    decision.
    D. The Consolidated Petition for Judicial Review. On June 9,
    10, and 11, 2015, Des Moines, Muscatine, and Cedar Rapids respectively
    filed separate petitions for judicial review under Iowa Code chapter 17A.
    These actions challenged the IDOT’s actions on various grounds, including
    (1) infringement of the Cities’ home rule authority; (2) lack of statutory
    authority for the IDOT to promulgate the rules; (3) a claim that the IDOT
    did not follow proper procedure in promulgating the rules, especially
    because the original, proposed rules had not contained a 1000-foot rule;
    and (4) a claim that the IDOT’s directives under the rules to remove or
    disable specific ATE equipment were arbitrary and capricious. The actions
    were later consolidated into a single proceeding in the Iowa District Court
    for Polk County.
    11
    On March 27, 2017, the district court held a hearing, and the court
    subsequently issued an order on April 25.
    The district court’s order upheld both the IDOT’s rules and its
    decisions based on those rules.      In dismissing the Cities’ home rule
    argument, the court noted, “Pursuant to Section 306.4(1), the IDOT
    implemented rules governing the minimum requirements for ATEs, their
    evaluation, and their subsequent removal if necessary. 
    Iowa Admin. Code r. 761
    —144. Therefore, state law, through the IDOT administrative rules,
    controls.”
    The court also found that the IDOT had sufficient authority under
    the Iowa Code to promulgate the subject ATE rules. It stated,
    The “jurisdiction and control over the primary roads
    shall be vested in the [IDOT].” [Iowa Code] § 306.4(1). To carry
    out these statutory provisions, the IDOT adopted rules
    regulating ATEs emphasizing safety. See 
    Iowa Admin. Code r. 761
    —144.6(1).         This is consistent with regulating
    obstructions in highway right-of-ways; the construction,
    improvement, operation or maintenance of any highway; and
    limiting cities’ obstruction of a street or highway which is used
    as an extension of a primary road. See Iowa Code Chapter
    318; 
    Iowa Code §§ 306.4
    , 321.348.
    (First alteration in original.)
    The district court further concluded that the rules had been
    promulgated in accord with a proper procedure, noting,
    At the meetings and during the public hearing, comments
    specifically citing the 1,000ft rule were submitted. Therefore,
    the 1,000ft rule is a direct result of public comments made
    and is, at the very least, a logical outgrowth of overall public
    comments. Since final administrative rules may differ from
    proposed rules, an additional notice and comment period is
    not required and the IDOT decisions and orders pursuant to
    the rule are valid.
    Finally, the district court concluded that the application of the rules
    to the Cities’ ATE systems complied with chapter 17A because the IDOT’s
    12
    review of the statistics and data was comprehensive, reviewing more than
    simply speed data or crash data. The court concluded that the IDOT’s
    actions were reasonable and logical and thus did not violate chapter 17A.
    The Cities appealed the district court’s rulings on all of these issues,
    and we retained the appeal.
    II. Standard of Review.
    “Judicial review of agency decisions is governed by Iowa Code
    section 17A.19.” Brakke v. Iowa Dep’t of Nat. Res., 
    897 N.W.2d 522
    , 530
    (Iowa 2017) (quoting Kay-Decker v. Iowa State Bd. of Tax Review, 
    857 N.W.2d 216
    , 222 (Iowa 2014)). We use the standards set forth in section
    17A.19(10) “to determine if we reach the same results as the district court.”
    
    Id.
     (quoting Renda v. Iowa Civil Rights Comm’n, 
    784 N.W.2d 8
    , 10 (Iowa
    2010)).
    To resolve whether the IDOT had authority to promulgate the ATE
    rules, we must determine whether its action was “[b]eyond the authority
    delegated to the agency by any provision of law or in violation of any
    provision of law.” Iowa Code § 17A.19(10)(b).
    Historically, we have said that an agency rule is “presumed valid
    unless the party challenging the rule proves ‘a “rational agency” could not
    conclude the rule was within its delegated authority.’ ” Meredith Outdoor
    Advert., Inc. v. Iowa Dep’t of Transp., 
    648 N.W.2d 109
    , 117 (Iowa 2002)
    (quoting Milholin v. Vorhies, 
    320 N.W.2d 552
    , 554 (Iowa 1982) (en banc));
    see also Brakke, 897 N.W.2d at 533.
    However, “[t]he power of the agency is limited to the power granted
    by statute.” Brakke, 897 N.W.2d at 533. In Brakke, we emphasized that
    “ultimately the interpretation and construction of a statute is an issue for
    the court to decide.” Id. We do not defer to the agency’s interpretation of
    its own statutory authority to issue a rule unless “the legislature has
    13
    clearly vested that interpretation in the agency.” Id. This is consistent
    with our Renda line of cases. See 
    784 N.W.2d at 13
    .
    For example, in Kopecky v. Iowa Racing & Gaming Commission, we
    declined to defer to the agency’s interpretation of its own authority to issue
    a rule allowing it consider the economic effect of a new gaming operation
    on existing facilities because “we [were] not firmly convinced the legislature
    vested the Commission with the authority to interpret our statutes when
    it enacts its rules.” 
    891 N.W.2d 439
    , 442 (Iowa 2017).
    Similarly, we are not persuaded here that the legislature clearly
    vested the IDOT with interpretive authority to determine its own authority.
    None of the relevant statutes expressly give the IDOT interpretive
    authority. Cf. Iowa Med. Soc’y v. Iowa Bd. of Nursing, 
    831 N.W.2d 826
    ,
    827, 829–30, 841 (Iowa 2013) (noting that Iowa Code section 147.76
    expressly grants the nursing board interpretive authority and applying a
    deferential standard in determining that the board had authority to issue
    certain rules).
    As justification for the rules, the IDOT relies in part on general
    provisions. See 
    Iowa Code § 306.4
    (1) (providing that “[j]urisdiction and
    control over the primary roads shall be vested in the department”); 
    id.
    § 307.12(1)(j) (granting authority to “[a]dopt rules . . . as the director deems
    necessary for the administration of the department and the exercise of the
    director’s and department’s powers and duties”).            These provisions,
    however, contain generic terms like “jurisdiction” and “deems necessary.”
    Such terms are widely used in “other areas of law” besides transportation
    and are not “specialized terms within the expertise of the agency.” Renda,
    
    784 N.W.2d at 14
    .
    The IDOT also relies on its authority to eliminate “obstructions” from
    highway rights-of-way as found in Iowa Code chapter 318.               But the
    14
    legislature has provided its own definition of “obstruction.” 
    Iowa Code §§ 318.1
    (4), .3. This typically presents an “insurmountable obstacle” to
    the conclusion that the IDOT has been vested with interpretive authority
    over the term. See Iowa Dental Ass’n v. Iowa Ins. Div., 
    831 N.W.2d 138
    ,
    145 (Iowa 2013). On the contrary, “it indicates we ought to apply the
    legislative definition ourselves.”   
    Id.
       Accordingly, we must determine
    ourselves whether the ATE rules are “[b]eyond the authority delegated to
    the agency by any provision of law or in violation of any provision of law.”
    Iowa Code § 17A.19(10)(b).
    In considering whether the agency followed proper rulemaking
    procedure under Iowa Code section 17A.4, we apply the relevant standards
    of section 17A.19(10). See Iowa Fed’n of Labor, AFL–CIO v. Iowa Dep’t of
    Job Serv., 
    427 N.W.2d 443
    , 445 (Iowa 1988) (en banc) (applying section
    17A.19(8), now section 17A.19(10)); see also Teleconnect Co. v. Iowa State
    Commerce Comm’n, 
    404 N.W.2d 158
    , 162 (Iowa 1987) (same). The test is
    one of substantial compliance with section 17A.4. Iowa Fed’n of Labor,
    
    427 N.W.2d at 450
    ; see Iowa Code § 17A.4(5).
    When the question is whether the agency erred in applying its rules,
    “then the challenge is to the agency’s application of the law to the facts,
    and the question on review is whether the agency abused its discretion by,
    for example, employing wholly irrational reasoning or ignoring important
    and relevant evidence.” Meyer v. IBP, Inc., 
    710 N.W.2d 213
    , 219 (Iowa
    2006); see also Iowa Code § 17A.19(10)(l); Neal v. Annett Holdings, Inc., 
    814 N.W.2d 512
    , 518 (Iowa 2012).
    III. IDOT’s Authority to Promulgate the ATE Rules.
    The Cities first contend that the IDOT exceeded its statutory
    authority in promulgating the ATE administrative rules. Although this is
    framed as both a home rule argument and an argument that the IDOT
    15
    went beyond its own statutory authority in issuing the rules, the
    arguments are really one and the same.
    Within Iowa’s constitutional and statutory framework, the Cities
    have retained certain rights, “except as expressly limited by the
    Constitution of the State of Iowa, and if not inconsistent with the laws of
    the general assembly.” See 
    Iowa Code § 364.1
     (emphasis added); see also
    Iowa Const. art. III, § 38A (“Municipal home rule”).      Therefore, despite
    home rule, state law, implemented through valid administrative rule, will
    displace an otherwise valid municipal ordinance. See 
    Iowa Code § 364.1
    ;
    see also Iowa Const. art. III, § 38A. However, invalid state administrative
    rules cannot be enforced against a municipality. Cf. City of Coralville v.
    Iowa Utils. Bd., 
    750 N.W.2d 523
    , 529 (Iowa 2008).         The issue thus is
    whether the IDOT had the authority to promulgate the rules to begin with.
    Since we conclude they do not have the authority to do so, such rules are
    unenforceable against the Cities and there is no conflict between the rules
    and the Cities’ ordinances.
    In City of Davenport v. Seymour, we addressed whether municipal
    ordinances regarding ATE systems were preempted by state law (not state
    administrative rules). 
    755 N.W.2d 533
    , 535 (Iowa 2008). We held that the
    legislature had not preempted a Davenport ATE ordinance. 
    Id.
     at 535–36.
    That case did not involve a conflict with the IDOT, nor did it involve agency
    action at all; the question was whether the ordinance conflicted with the
    statutory provisions. 
    Id.
     The statutes at issue in that case were the “traffic
    regulation and enforcement provisions of Iowa Code chapter 321 (laws of
    the road) and sections 364.22(5)(b) (municipal infractions), 805.6 (form of
    citation in criminal cases), and 805.8A (schedule of criminal fines).” 
    Id. at 537
    . This case presents a different question: a conflict between municipal
    action and state administrative rules.
    16
    Ordinarily, state agency rules are given the “the force and effect of
    law.” Stone Container Corp. v. Castle, 
    657 N.W.2d 485
    , 489 (Iowa 2003)
    (quoting Greenwood Manor v. Iowa Dep’t of Pub. Health, 
    641 N.W.2d 823
    ,
    835 (Iowa 2002)). However, “agencies have ‘no inherent power and [have]
    only such authority as [they are] conferred by statute or is necessarily
    inferred from the power expressly given.’ ” Wallace v. Iowa State Bd. of
    Educ., 
    770 N.W.2d 344
    , 348 (Iowa 2009) (alterations in original) (quoting
    Zomer v. W. River Farms, Inc., 
    666 N.W.2d 130
    , 132 (Iowa 2003)). For a
    rule to be validly adopted, it “must be within the scope of the powers
    delegated to [the agency] by statute.” 
    Id.
     (quoting Iowa Power & Light Co.
    v. Iowa State Commerce Comm’n, 
    410 N.W.2d 236
    , 239 (Iowa 1987)). Thus,
    if the rules adopted by the agency “exceed the agency’s statutory authority,
    the rules are void and invalid.” 
    Id.
     “An agency cannot by rule . . . expand
    or limit authority granted by statute.” Smith–Porter v. Iowa Dep’t of Human
    Servs., 
    590 N.W.2d 541
    , 545 (Iowa 1999).
    In deciding whether the ATE administrative rules promulgated by
    the IDOT were validly adopted, we must determine whether their adoption
    was within the scope of authority delegated to the IDOT by the legislature.
    “We have declined to find legislative authorization for agency rulemaking
    in the absence of a specific grant of authority.” Wallace, 
    770 N.W.2d at 348
    .   When the legislature has given an agency general rulemaking
    authority but has also granted specific authority in particular areas, the
    agency cannot then extend the specific grants beyond their scope.
    Our cases reflect this principle.   In Brakke, we found that the
    specific legislative grant of authority to promulgate rules “for the
    quarantine of diseased preserve whitetail” could not be used by the
    department of natural resources (DNR) to promulgate rules allowing the
    quarantine of (1) nondiseased deer that had also been exposed to the
    17
    disease or (2) the land where the diseased deer had been. 897 N.W.2d at
    531, 541–42 (quoting Iowa Code § 484C.12(1)).
    We therefore conclude that Iowa Code section 484C.12
    should be read according to its ordinary meaning. The
    consequence of this interpretation is that the agency lacked
    the statutory authority to promulgate the administrative rule
    expanding the scope of quarantines to include fencing of lands
    for a five-year period when all diseased preserve wildlife have
    been eradicated.      As a result, the agency was without
    authority to issue the emergency order in this case. If the
    legislature wishes to expand quarantine powers as suggested
    by the DNR rule, it is, of course, free to do so.
    Id. (footnote omitted). We reached this conclusion even though “Iowa Code
    chapter 484C generally grants DNR the authority to regulate preserve
    whitetail.” Id. at 531; see Iowa Code § 484C.2(2) (“This chapter authorizes
    the department of natural resources to regulate preserve whitetail.”).
    We applied similar reasoning in Wallace.       There, the plaintiffs
    challenged a school district’s decision to close five elementary schools on
    the ground the school district had failed to comply with rules promulgated
    by the state board of education regarding school closure decisions. 
    770 N.W.2d at 346
    . The school district responded that the board of education
    did not have the authority to promulgate those rules, rendering them
    invalid. 
    Id.
     The board had been authorized by statute to “[a]dopt rules
    under chapter 17A for carrying out the responsibilities of the department.”
    
    Id. at 348
     (alteration in original) (quoting 
    Iowa Code § 256.7
    (5) (2003)).
    However, we found that this language did not grant the board “unlimited
    power to regulate matters within the agency’s expertise.”        
    Id.
         The
    legislature had expressly authorized the board to adopt rules regarding
    many other areas, but not school closures. 
    Id.
     at 348–49. We concluded
    that “the notable absence of a legislative grant to the [state board] of
    authority to adopt rules regulating school closure decisions” meant that
    18
    such power was not within the scope of its authority. 
    Id. at 349
    . Therefore,
    the rules were void. 
    Id.
    Likewise, in Litterer v. Judge, we rejected an effort to force the
    secretary of agriculture to adopt rules mandating ten percent ethanol
    content in all motor vehicle fuel sold in Iowa. 
    644 N.W.2d 357
    , 359–60
    (Iowa 2002). The secretary had refused to promulgate such a rule on the
    basis that she lacked the legislative authority to do so. 
    Id. at 360
    . The
    statute at issue provided,
    The secretary shall adopt rules pursuant to chapter 17A for
    carrying out this chapter. The rules may include, but are not
    limited to, specifications relating to motor fuel or oxygenate
    octane enhancers. In the interest of uniformity, the secretary
    shall adopt by reference or otherwise specifications relating to
    tests and standards for motor fuel or oxygenate octane
    enhancers, established by the American society for testing
    and materials (A.S.T.M.), unless the secretary determines
    those specifications are inconsistent with this chapter or are
    not appropriate to the conditions which exist in this state.
    
    Id. at 363
     (emphasis omitted) (quoting Iowa Code § 214A.2(1) (1999)).
    In other words, Iowa law gave the secretary of agriculture authority
    to adopt rules to carry out the motor vehicle fuel statutes, including the
    express authority to promulgate rules relating to specifications for motor
    fuel. Id. Nonetheless, we rejected the plaintiffs’ appeal because there was
    “no specific grant of authority by the legislature in section 214A.2
    permitting the secretary to regulate the content level of ethanol in motor
    fuel.” Id. In our examination of the legislative history and the meaning of
    other terms in the statute, we did not find evidence of legislative intent to
    bestow this authority. See id. at 363–65. Therefore, despite the existence
    of a closely related grant of authority, we decided the statute did not confer
    authority to promulgate rules mandating ethanol content. See id. at 365.
    19
    In another case, we found that the DNR lacked statutory authority
    to issue an administrative order pertaining to the cleanup of solid waste.
    First Iowa State Bank v. Iowa Dep’t of Nat. Res., 
    502 N.W.2d 164
    , 168 (Iowa
    1993). The DNR had determined that a bank foreclosing on property was
    responsible for the cost of cleanup of illegally dumped solid waste on the
    site. 
    Id. at 165
    . We acknowledged that “[s]pecific statutory authority for
    adopting administrative rules relating to solid waste is provided in section
    455B.304.” 
    Id. at 168
    . However, we also noted that “no reference is made
    to adoption of rules relating to cleanup of open dumps.” 
    Id.
     Additionally,
    Iowa law imposed liability “for cleanup of a hazardous condition . . . upon
    a person having control over the hazardous substance.” 
    Id.
    Given these statutory provisions, we reasoned that the DNR lacked
    the necessary authority. 
    Id.
     Interpreting the statute to provide the agency
    with authority to issue the administrative order would have imposed
    broader liability for cleanup of solid waste than for cleanup of hazardous
    waste—contrary to the underlying statutory scheme. See 
    id.
     We agreed
    with the district court that “the action of the DNR is in excess of the
    statutory authority granted to it.” 
    Id.
    Barker v. Iowa Department of Transportation also found that the
    department of transportation had exceeded its rulemaking authority. 
    431 N.W.2d 348
     (Iowa 1988). There, the department revoked a driver’s license
    on the basis of a breath test that had indicated a blood alcohol content of
    .108%. 
    Id.
     at 348–49. The legal challenge concerned department rules
    that had established the margin of error for a blood test at plus or minus
    five percent. 
    Id. at 349
    . The underlying statute referenced an “established
    margin of error” but neither designated that margin nor expressly
    authorized the department to make the designation.        
    Id.
     (quoting Iowa
    Code § 321J.12 (1987)).       Because the administrative rules review
    20
    committee challenged the rule, the burden was on the agency to establish
    its authority to promulgate the rule. Id. The department pointed to its
    general statutory authority to promulgate administrative rules to carry out
    any laws whose enforcement was vested in the department. Id. at 350.
    However, we found that the department lacked the authority to establish
    a standard for what would constitute a violation, as such a power must be
    expressly given. Id. (“Authority for such a power cannot be implied . . . .”).
    The authority to approve devices could not be broadly interpreted as
    including authority to promulgate a rule “establishing a margin of error for
    the devices it has approved.” Id.
    In another case, several public utility companies challenged the
    state commerce commission’s authority to promulgate a rule requiring
    utility financing of energy conservation measures. Iowa–Ill. Gas & Elec.
    Co. v. Iowa State Commerce Comm’n, 
    334 N.W.2d 748
    , 749 (Iowa 1983).
    There, we found that even the express statutory mandate that “[t]he
    commission shall promulgate rules concerning the use of energy
    conservation strategies by rate or service regulated gas and electric
    utilities” was not sufficient to confer authority to promulgate rules
    requiring utility financing of conservation measures. 
    Id. at 752
     (quoting
    
    Iowa Code § 476.2
     (1981)). “Such commission authority, if it exists, must
    be implied from the statutory language the commission relies on.” 
    Id.
    Using the ordinary meaning of the statutes, we concluded that the phrases
    “programs designed to promote” and “rules concerning the use of” meant
    the commission had the authority “to encourage, influence, and provide
    incentives relating to energy conservation.” 
    Id.
     However, that still was not
    enough to give the authority to require utility financing of energy
    conservation, undeniably a method of achieving energy conservation. 
    Id.
    We found that the Code provisions “relied on by the commission do not
    21
    mention financing at all, let alone permit it.” 
    Id. at 753
    . Therefore, the
    commission did not have the authority to promulgate rules requiring
    utility financing. 
    Id.
     Because the authority to require financing was a
    “departure from traditional utilities regulation,” we concluded “that it must
    be clearly manifested by legislative enactment.” 
    Id. at 754
    .
    In Marquart v. Maucker, an employee of a state university
    successfully contested an administrative rule that had resulted in
    withholding from her final paycheck. 
    215 N.W.2d 278
    , 279 (Iowa 1974).
    The university had established various rules and regulations for the use
    of its parking lots, enforceable by fines that could be deducted from an
    employee’s paycheck. 
    Id.
     The university put forth several statutes that it
    claimed as the basis of its authority, including the authority to set speed
    limits, but we found that these statutes could not imply the authority to
    adopt the parking regulations in question. See 
    id. at 282
    .
    The foregoing cases follow a pattern. In Brakke, Wallace, Litterer,
    First Iowa State Bank, Barker, Iowa–Illinois Gas & Electric, and Marquart,
    the legislature gave the agency authority to issue rules in a specific area,
    but not the specific area at issue.       Accordingly, we found that an
    overarching general grant of authority was an insu
    fficient basis for rulemaking in that area.
    Even when we have upheld the agency’s authority to promulgate
    rules, we first determined that the legislature had expressly granted
    statutory authority to promulgate rules related to the subject area. For
    example, in Meredith Outdoor Advertising, Inc., we found that the IDOT
    could promulgate rules requiring the revocation of permits when billboard
    sign owners reconstructed or modified nonconforming signs more than
    660 feet from an interstate without seeking a new permit. 
    648 N.W.2d at
    116–17. There, the plaintiff appealed a decision by the IDOT revoking two
    22
    permits for outdoor advertising signs after the signs were reconstructed or
    modified without the plaintiff having obtained new permits. 
    Id. at 112
    .
    This was in violation of the IDOT’s administrative rule. 
    Id.
     The plaintiff
    contended that the rule exceeded the IDOT’s rulemaking authority,
    pointing to the fact that a different chapter, 306B, specifically granted
    authority to the department to “promulgate and enforce rules . . .
    governing the erection, maintenance, and frequency of advertising devices
    within six hundred sixty feet of the edge of the right of way.” 
    Id. at 116
    (omission in original) (quoting Iowa Code § 306B.3 (1999)). Nevertheless,
    we found that “several other statutory sections inherently provide the
    department with sufficient authority to enact regulations controlling the
    maintenance of nonconforming signs.” Id. at 117. We concluded that “the
    legislature intended to provide the department with the power to fill in any
    gaps within chapter 306C by enacting administrative rules.” Id.
    We noted in Meredith Outdoor Advertising that Iowa Code section
    306C.12 generally prohibited the signs in question.            Id. at 115.
    Additionally, “[s]ections 306C.18(3) and 306C.19 require sign owners such
    as [the plaintiff] to follow department rules or be subject to removal.” Id.
    at 117. Furthermore, “[a]dditional sections provide general authority to
    the department to adopt such rules deemed necessary to carry out its
    duties.” Id. Based on this combination of authority, we found the rule
    was within the IDOT’s delegated authority. See id.
    In Overton v. State, a prison inmate challenged the authority of the
    Iowa Department of Corrections to make rules requiring him to reimburse
    a staff member for eyeglasses broken during an altercation. 
    493 N.W.2d 857
    , 858 (Iowa 1992).     The contested rule permitted the sanction of
    “assessed costs” when an inmate violated a disciplinary rule. 
    Id. at 859
    .
    Iowa law provided, “Inmates who disobey the disciplinary rules of the
    23
    institutions to which they are committed shall be punished by the
    imposition of the penalties prescribed in the disciplinary rules. . . .” 
    Id.
    (omission in original) (quoting 
    Iowa Code § 246.505
    (1)). We found that the
    department had the necessary authority because the assessed costs
    constituted a penalty. 
    Id.
    In Frank v. Iowa Department of Transportation, we were charged with
    deciding “whether the department was within its statutory authority to
    conclude under its rules that a moving traffic-law violation includes failing
    to have a valid chauffeur’s license.” 
    386 N.W.2d 86
    , 88 (Iowa 1986). We
    determined that it was, particularly noting the statutory basis for the
    authority to promulgate such rules:
    Section 321.210 authorizes the department to establish
    rules for license suspension if the operator is found to be a
    habitual violator, and provides only three exclusions for
    violations of statutory or municipal ordinances in determining
    whether or not to suspend a license. Pursuant to this section,
    the department defines a “habitual violator” as one who has
    convictions for more than two moving traffic-law violations
    within twelve months. It then defines “moving traffic law
    violation” as “any traffic law violation except” ones regarding
    equipment, parking, registration laws, expired licenses or
    permits, failures to appear, weights and measures, and
    disturbing the peace. There are no exceptions for failing to
    have a valid chauffeur’s license.
    
    Id.
     (citations omitted). We pointed out that “the legislature itself did not
    see fit to include . . . the failure to have a valid chauffeur’s license in its
    exemptions in section 321.210.” 
    Id.
     We concluded that the department
    “may properly consider the failure to have a valid chauffeur’s license to be
    a moving traffic-law violation under its rules.” See 
    id.
    In Milholin, we “decide[d] the validity and effect of a rule of the Iowa
    Real Estate Commission requiring all real estate listing agreements to be
    in a writing containing all essential terms.”     
    320 N.W.2d at 553
    .       The
    district court had found the rule to be invalid. 
    Id.
     We reversed, deciding
    24
    that the rule was a valid exercise of the commission’s authority. 
    Id.
     The
    relevant chapter vested the commission “with far-reaching authority to
    license, regulate and discipline brokers and salespersons.” 
    Id. at 554
    . The
    commission also had express, general rulemaking authority. 
    Id.
     Although
    the statute did not grant the specific authority to promulgate rules on this
    subject, the rule was nevertheless a regulatory measure over brokers and
    salespersons, thus allowing the commission to reasonably conclude that
    promulgating this rule fell within its statutory authority. See 
    id.
    In Temple v. Vermeer Manufacturing Co., we concluded that a rule
    promulgated by the industrial commissioner was within its specific
    statutory authority. 
    285 N.W.2d 157
    , 159–60 (Iowa 1979). The rule at
    issue there required the commissioner “to decide an appeal on the record
    established before the deputy commissioner unless the commissioner is
    satisfied that additional evidence is material and that there was good
    reason for failure to present the additional evidence to the deputy
    commissioner.” 
    Id. at 159
    . We concluded that the rule was “well within
    the legislative authorization.” 
    Id.
     There, the statute provided, “In addition
    to the provisions of section 17A.15, the industrial commissioner, on
    appeal, may limit the presentation of evidence as provided by rule.” 
    Id.
    (quoting 
    Iowa Code § 86.24
     (1979)). We noted that section 86.24 was a
    “particular statutory basis for the rule,” and thus the rule was within the
    commissioner’s authority. 
    Id. at 160
    .
    Meredith Outdoor Advertising, Overton, Frank, and Temple fall into
    the pattern we have already noted. In those cases, legislation gave the
    agency specific authority to decide when billboards could be permitted that
    were visible from an interstate highway (although more than 660 feet away
    from the highway), impose penalties, define a moving violation, and limit
    evidence. Thus, in each of those cases, the agency rule was upheld. As
    25
    noted, the trend of the above cases is that when the statute has granted
    general rulemaking authority and followed it up with specific authority
    over particular areas, the agency is not free to interpret the general
    rulemaking authority as granting unlimited rulemaking authority. Neither
    may the agency interpret the specific grants of authority broadly so as to
    encompass areas not clearly included within those grants.
    Milholin is, perhaps, more difficult to reconcile with the rest of the
    caselaw. The real estate commission had been given authority over the
    licensing, regulation, and disciplining of brokers and salespersons. 
    320 N.W.2d at 554
    . We concluded that a rule requiring listing agreements to
    be in writing was a rational way to “regulat[e] broker conduct to protect
    the public.” 
    Id.
     Milholin was decided thirty-six years ago and should be
    read along with more recent decisions. 3
    We turn now to the IDOT’s asserted basis for authority here. The
    IDOT points to its specific statutory authority to remove “obstructions”
    from the highway right-of-way of the primary highway system. See 
    Iowa Code §§ 318.4
    , .7 (2013). However, an “obstruction”
    means an obstacle in the highway right-of-way or an
    impediment or hindrance which impedes, opposes, or
    interferes with free passage along the highway right-of-way,
    not including utility structures installed in accordance with
    an approved permit.
    
    Id.
     § 318.1(4). The legislation continues,
    3Notably,   a dissenting opinion urged,
    The subject of the form or contents of contracts between realtors
    and listers does not come within the scope of the chapter. We are already
    inundated by a proliferation of agency rules. I do not think we should
    enlarge agencies’ rule-making powers additionally by construing statutes
    beyond what appears to be legislative intent in those statutes.
    Milholin, 
    320 N.W.2d at 556
     (Uhlenhopp, J., dissenting).
    26
    A person shall not place, or cause to be placed, an
    obstruction within any highway right-of-way. This prohibition
    includes, but is not limited to, the following actions:
    1. The excavation, filling, or making of any physical
    changes to any part of the highway right-of-way, except as
    provided under section 318.8.
    2. The cultivation or growing of crops within the
    highway right-of-way.
    3. The destruction of plants placed within the highway
    right-of-way.
    4. The placing of fences or ditches within the highway
    right-of-way.
    5. The alteration of ditches, water breaks, or drainage
    tiles within the highway right-of-way.
    6. The placement of trash, litter, debris, waste material,
    manure, rocks, crops or crop residue, brush, vehicles,
    machinery, or other items within the highway right-of-way.
    7. The placement of billboards, signs, or advertising
    devices within the highway right-of-way.
    8. The placement of any red reflector, or any object or
    other device which shall cause the effect of a red reflector on
    the highway right-of-way which is visible to passing motorists.
    
    Id.
     § 318.3.
    The list of potential obstructions in Iowa Code section 318.3 does
    not include ATE equipment, nor does it include anything comparable to
    ATE equipment. Id. § 318.3. The first seven items consist of physical
    obstacles within the right-of-way. Id. § 318.3(1)–(7). The last item, a “red
    reflector,” is presumably included because a red reflector is a recognized
    warning device for motorists. See id. § 321.389 (requiring a red reflector
    on the rear of all vehicles). Therefore, a red reflector that wasn’t warning
    27
    about a vehicle or other hazard could throw motorists off the track and
    itself pose a danger. 4
    Significantly, Iowa Code chapter 318 requires every “obstruction” to
    be removed and provides that any person who places an “obstruction” in
    a highway right-of-way is deemed to have created a public nuisance. See
    id. §§ 318.5(1)–(2), .6(1) (2013).          So if the IDOT’s interpretation were
    correct, the Cities would be creating a public nuisance.                        Also, the
    prohibition only applies to obstructions “within any highway right-of-way.”
    Id. § 318.3. Notably, all the interstate ATE systems at issue in this case
    were mounted on existing overhead truss signs. 5
    Reading chapter 318 as a whole, it is not plausible to use the term
    “obstruction” for a traffic camera that takes a photograph for law
    enforcement purposes of a vehicle going more than ten miles over the
    speed limit. 6
    The IDOT also relies on two broadly worded statutes: Iowa Code
    sections 307.2 and 307.12(1)(j). The former states that the IDOT “shall be
    responsible for the planning, development, regulation and improvement of
    4Chapter 318 was enacted in 2006. 2006 Iowa Acts ch. 1097. Its predecessor,
    chapter 319, contained a provision that served a similar purpose:
    Except for official traffic-control devices as defined by section
    321.1, subsection 46, no person shall place, erect, or attach any red
    reflector, or any object or other device which shall cause a red reflectorized
    effect, within the boundary lines of the public highways so as to be visible
    to passing motorists.
    
    Iowa Code § 319.12
     (2005).
    5Inseveral instances, the IDOT gave the Cities the option of disabling, rather than
    removing, the ATE equipment. If the equipment were really an “obstruction” within the
    meaning of chapter 318, disabling would not be a remedy.
    6Similarly,    we do not believe that the IDOT had authority to promulgate the rules
    under Iowa Code section 321.348, which makes it “unlawful for any city to close or
    obstruct any street or highway which is used as the extension of a primary road within
    such city . . . .” 
    Iowa Code § 321.348
    . Whatever their merits or demerits, the ATE systems
    are not an “obstruction.”
    28
    transportation in the state as provided by law.”              
    Id.
     § 307.2.     Section
    307.12(1)(j) authorizes the director of the department to “[a]dopt rules in
    accordance with chapter 17A as the director deems necessary for the
    administration of the department and the exercise of the director’s and
    department’s powers and duties.” Id. § 307.12(1)(j).
    The IDOT argues that these general provisions sustain the ATE
    rules. However, neither of these two provisions broadens the reach of the
    IDOT; rather, each incorporates and relies upon other legal sources. Iowa
    Code section 307.2 states that the IDOT is responsible for the regulation
    of transportation “as provided by law.” Section 307.12 empowers the IDOT
    to adopt rules to exercise its “powers and duties.” In other words, the
    IDOT can adopt rules, but they have to be in furtherance of legal authority
    that the agency otherwise possesses.
    The IDOT’s argument runs contrary to our prior holdings in Wallace,
    Litterer, Iowa–Illinois Gas & Electric, Barker, Brakke, and First Iowa State
    Bank. For example, in Wallace we said, “[G]eneral authorization of this
    type does not grant to an administrative agency unlimited power to
    regulate matters within the agency’s expertise.”              
    770 N.W.2d at 348
    .
    Furthermore, the delegation of authority to the IDOT over other specific
    areas prevents the IDOT from claiming specific authority here. 7
    The other statutes cited by the IDOT as authority for promulgating
    the ATE rules are similarly generic and not specific to ATE systems. Iowa
    Code section 306.4(1) states that “[j]urisdiction and control over the
    7Our   decision in Lenning v. Iowa Department of Transportation provides a useful
    contrast to the present case. 
    368 N.W.2d 98
     (Iowa 1985). There we upheld an IDOT rule
    that made persons with prior license revocations based upon OWI convictions ineligible
    for work permits during the period of a subsequent revocation. 
    Id. at 100
    . Although we
    quoted the IDOT’s general rulemaking authority in a footnote, we sustained the rule
    because the underlying statute specifically gave the IDOT discretion on whether to issue
    temporary restricted licenses in these circumstances. 
    Id.
     at 101–02 & n.1.
    29
    primary roads shall be vested in the department.” 
    Iowa Code § 306.4
    (1).
    Section 306.4(4)(a) provides,
    Jurisdiction and control over the municipal street system
    shall be vested in the governing bodies of each municipality;
    except that the department and the municipal governing body
    shall exercise concurrent jurisdiction over the municipal
    extensions of primary roads in all municipalities. When
    concurrent jurisdiction is exercised, the department shall
    consult with the municipal governing body as to the kind and
    type of construction, reconstruction, repair, and maintenance
    and the two parties shall enter into agreements with each
    other as to the division of costs thereof.
    
    Id.
     § 306.4(4)(a). The IDOT argues that “[s]ections 306.4(1) and 306.4(4)(a)
    should be read together and harmonized with the DOT having final
    authority to adopt the subject ATE rules.”
    We are not persuaded.      We think that the ordinary meaning of
    “jurisdiction and control over the primary roads” in this context means
    that the department has authority over the establishment, alteration, and
    vacation of such roads.    Those are the subjects covered by Iowa Code
    chapter 306. See City of Cedar Rapids v. State, 
    478 N.W.2d 602
    , 605 (Iowa
    1991) (“We believe that the intent and purpose of [section 306.4(3) (now
    306.4(4))] is to establish the jurisdiction and control of municipalities in
    the establishment, alteration, and vacation of roadways within the
    municipal limits.”).
    The IDOT’s argument proves too much. Suppose the Cities decided
    to station numerous patrol cars on Interstates 380 and 235 and Highway
    61 to catch and ticket speeders. Could the IDOT issue a rule banning the
    practice on the ground that it has “jurisdiction and control” over these
    roads? Clearly not.
    Furthermore, Iowa Code section 321.285(5) gives the IDOT authority
    to establish speed limits under circumstances on “fully controlled-access
    30
    . . . highways.” See 
    Iowa Code § 321.285
    (5). But missing from this specific
    grant is any authority over methods of enforcing speed limits. See Litterer,
    
    644 N.W.2d at 365
    .
    Brakke is instructive here, because it is in many ways analogous to
    the present case. 
    897 N.W.2d 522
    . Like the IDOT, the DNR possesses
    broad authority over its domain. Section 455A.2 states, “A department of
    natural resources is created, which has the primary responsibility for state
    parks and forests, protecting the environment, and managing fish, wildlife,
    and land and water resources in the state.”           Iowa Code § 455A.2.
    Furthermore, Iowa Code section 484C.2(2) “authorizes the department of
    natural resources to regulate preserve whitetail,” and the DNR is imbued
    with a statutory authority to “adopt rules pursuant to chapter 17A as
    necessary to administer” the chapter regarding whitetail deer.             Id.
    § 484C.3.
    Nonetheless, in Brakke, we found that the DNR could not
    promulgate quarantine rules outside the particular scope of section
    484C.12, even though those rules might appear otherwise consistent with
    the broad rulemaking authority and legislative intent to protect whitetail
    deer. 897 N.W.2d at 533–34. We noted the department’s argument that
    the clear legislative intent was to eradicate the particular disease at issue,
    since it was mentioned by name by the legislature. Id. at 532 (“According
    to the DNR, it would make no sense for a legislature so concerned with
    [this disease] to deny the state regulatory authorities the ability to protect
    the whitetail population from a primary pathway for transmission of the
    disease, namely exposure to prion-contaminated land.”). The expanded
    quarantine was certainly consistent with that goal.       See id.   Still, the
    rulemaking authority given to the department did not extend beyond the
    type of quarantine referred to in Iowa Code section 484C.12(1). Id. at 541.
    31
    Likewise, here, the IDOT’s general mission to preserve motorist
    safety is not enough to allow it to deviate from its specific statutory
    authority, by treating an ATE system as a right-of-way obstruction. As we
    said in Brakke, if the legislature wants to expand the IDOT’s powers to
    include regulation of ATE systems, “it is, of course, free to do so.” Id. at
    541–42.
    Other state legislatures have expressly vested state agencies with
    authority over ATE systems.            See, e.g., 
    Ariz. Rev. Stat. Ann. § 28
    –641
    (Westlaw through 2d Reg. Sess. 2018) (giving the department of
    transportation the authority to “adopt a manual and specifications for a
    uniform system of control devices,” including photo enforcement systems);
    625 Ill. Comp. Stat. Ann. 7/10 (West, Westlaw through P.A. 100–585 of
    2018 Reg. Sess.) (granting the department of state police the authority to
    establish ATE systems); Md. Code. Ann., Transp. § 25-104 (West, Westlaw
    through 2018 Reg. Sess.) (“The State Highway Administration shall adopt
    a manual and specifications for a uniform system of traffic control
    devices,” including automatic speed monitoring systems). To date, our
    general assembly has not pursued this course of action. 8
    The IDOT contends that by not enacting legislation to overturn the
    ATE rules, the legislature has impliedly endorsed them. The IDOT cites
    State v. Miner, where we said,
    The Iowa Administrative [P]rocedure Act affords the legislature
    an opportunity to object to agency rules and to override them
    by statute. These steps were not taken by the legislature;
    therefore, we assume that the legislature approved of the
    8As  noted, the legislature has specifically empowered the IDOT to act in other
    areas, but not with respect to ATE systems. We have long recognized the principle of
    expressio unius est exclusio alterius, i.e., the expression of one is the exclusion of the
    other, as an aid to statutory interpretation. See, e.g., Staff Mgmt. v. Jiminez, 
    839 N.W.2d 640
    , 649 (Iowa 2013); Thomas v. Gavin, 
    838 N.W.2d 518
    , 524 (Iowa 2013); Kucera v.
    Baldazo, 
    745 N.W.2d 481
    , 487 (Iowa 2008).
    32
    requirement that brokers be licensed as dealers and of the
    resulting application of the title requirements to all who
    initiate the retail sale of motor vehicles.
    
    331 N.W.2d 683
    , 687 (Iowa 1983) (citation omitted). However, Miner is
    distinguishable. Miner involved a specific grant of legislative authority to
    adopt the rule at issue. 
    Id. at 686
    . We found that the administrative rule
    “was only verbalizing what section 322.3(2) had already directed.” 
    Id.
     The
    administrative rule, in other words, “was following what the legislature had
    already directed in section 322.3(2).” 
    Id. at 687
    . Here, the rule lacks such
    support.    We are unwilling to adopt a principle that whenever the
    legislature declines to pass legislation overturning a rule, it has statutorily
    authorized that rule.    This flips article III and article IV of the Iowa
    Constitution.
    In 2014, the general assembly enacted a statutory ban on the use of
    drones for traffic law enforcement.     See 2014 Iowa Acts ch. 1111, § 1
    (codified at 
    Iowa Code § 321
    .492B) (2015). This shows that the legislature
    has the ability to enact laws regulating newer methods of traffic law
    enforcement.
    Therefore, we conclude that the IDOT did not have statutory
    authority to promulgate the administrative rules dictating placement and
    continued use of ATE equipment by the Cities. As a result, the agency was
    without authority to rely on those rules to order the Cities to move, remove,
    or disable their ATE systems.
    Because of our determination that the IDOT lacked authority to
    issue the ATE rules, we need not reach the Cities’ additional arguments
    that the IDOT failed to comply with proper rulemaking procedure in
    adopting the 1000-foot rule, or that the ATE rules and their application to
    the Cities were illogical and wholly irrational, failed to address relevant
    and important information that a rational decision-maker would consider,
    33
    and were otherwise arbitrary and capricious. See Iowa Code § 17A.4(1)(a);
    id. § 17A.19(10)(i), (j), (n).
    IV. Conclusion.
    We conclude that the IDOT was without statutory authority to
    promulgate its administrative rules regarding the municipalities’ ATE
    systems.    We reverse the district court’s order and remand for further
    proceedings consistent with this opinion.
    REVERSED AND REMANDED.
    All justices concur except Hecht, J., who takes no part.