IN THE SUPREME COURT OF IOWA 

No. 33 / 06–1753 

Filed August 29, 2008 

CITY OF DAVENPORT, 

 Appellee, 

vs. 

THOMAS J. SEYMOUR, 

 Appellant. 

 Appeal from the Iowa District Court for Scott County, Mary E. 

Howes, District Associate Judge. 

 Defendant challenges the legality of the Davenport Automated 

Traffic Enforcement ordinance. AFFIRMED. 

 Michael J. McCarthy of McCarthy, Lammers & Hines, Davenport, 

and Randall C. Wilson of ACLU of Iowa Foundation, Inc., Des Moines, for 

appellant. 

Christopher S. Jackson, Davenport, for appellee. 
2

APPEL, Justice. 

 In this case, the court must decide whether traffic regulations and 

enforcement mechanisms contained in Iowa Code chapter 321 and other 

code provisions were intended by the legislature to prohibit a 

municipality from establishing an automatic traffic enforcement system 

through which the city levels civil penalties against the owners of 

vehicles that fail to obey red light traffic signals or violate speed laws. 

Applying our well-established method of preemption analysis, we hold 

that the legislature has not preempted this automatic traffic enforcement 

ordinance through these statutory provisions. 

I. Factual and Procedural Background.

 If the twentieth century may be characterized as the Era of the 

Automobile, it was also the Era of Automobile Regulation. In 1902, 

officers in Westchester County, New York, concealed themselves in fake 

tree trunks at specified intervals and, armed with stop watches and 

telephones, attempted to detect and apprehend speeders. Not to be 

outdone, innovative constables in Massachusetts in 1909 deployed a 

method of detecting speeding motorists that used a combination of a 

camera and a stop watch. See Commonwealth v. Buxton, 91 N.E. 128 

(Mass. 1910). These comparatively simple approaches to traffic law 

enforcement were subsequently replaced in the 1940s and 1950s by 

“radar” detection systems. Attacked as Orwellian when first introduced, 

the use of radar is now a standard tool of law enforcement. 

 Innovation in traffic management has not been limited to speed 

control. As every motorist knows, automated stop lights have come to 

replace the blue-suited patrolman with outstretched arms engaged in 

perpetual motion with a whistle at the ready. Most municipal authorities 
3

believe police officers have better things to do than to control traffic at 

intersections. 

 Modern technological advances have also led to the development of 

more sophisticated “automated traffic enforcement” (ATE) systems. 

Using a combination of cameras and sensors, the ATEs allow municipal 

governments to detect traffic violations without a law enforcement officer 

present on the scene. Promoted by private vendors who have developed 

and operated the systems, ATE red light cameras were first deployed 

abroad over thirty-five years ago and according to industry sources are 

now operational in forty-five countries. Kevin P. Shannon, Speeding 

Towards Disaster: How Cleveland’s Traffic Cameras Violate the Ohio 

Constitution, 55 Clev. St. L. Rev. 607, 610 (2007). As of 2005, ATE speed 

detection systems were in use in as many as seventy-five countries. Id. 

In this country, speed cameras have been utilized on a limited 

basis in several states, including Arizona, California, North Carolina, 

Ohio, Oregon, and the District of Columbia. Red light systems have also 

been utilized by a number of municipalities, including those in Arizona, 

California, Virginia, and North Carolina. Id. at 611. 

The advent of automatic traffic enforcement has prompted 

legislative action in a number of jurisdictions. Some state legislatures 

have elected expressly to authorize local governments to establish ATE 

systems provided that certain statutory requirements are met, including 

posting notice to drivers that automated traffic devices are in use. See,

e.g., Colo. Rev. Stat. § 42–4–110.5 (2008); N.C. Gen. Stat. § 160A–300.1 

(2007). Other states have authorized ATE ordinances only in the vicinity 

of schools, residency zones, or railroad crossings. See, e.g., Ark. Code 

§§ 27–52–110, 27–52–111 (2007); Md. Code Ann., Transp. § 21–809 

(2008). Some states have explicitly prohibited their use. See, e.g., N.J. 
4

Stat. Ann. § 39:4–103.1 (2008); W. Va. Code § 17C–6–7a (2008); Wis. 

Stat. § 349.02(3) (2008). Most states, like Iowa, have no legislation 

directly addressing the issue. 

In 2004, the City of Davenport enacted an ordinance entitled 

“Automatic Traffic Enforcement.” Davenport Mun. Code § 10.16.070 

(2005). The Davenport ATE ordinance authorized the city to install 

cameras and vehicle sensors at various locations in the city to make 

video images of vehicles that fail to obey red light traffic signals or 

speeding regulations. The information obtained from these automated 

devices is then forwarded to the Davenport Police Department for review. 

The Davenport police then determine whether there has been a violation 

of the city’s traffic control ordinances. 

 Under the Davenport ATE ordinance, a vehicle owner is issued a 

notice and is liable for a civil fine as a result of any detected violation. A 

vehicle owner may rebut the city’s claim by showing that a stolen vehicle 

report was made on the vehicle which encompassed the time in which 

the violation allegedly occurred. Citations issued pursuant to the 

Davenport ATE ordinance are not reported to the Iowa Department of 

Transportation (IDOT) for the purpose of the vehicle owner’s driving 

record. 

 A recipient of an automated traffic citation may dispute the citation 

by requesting the issuance of a municipal infraction citation. If so 

disputed, the recipient is entitled to a trial before a judge or magistrate. 

In the event the disputing vehicle owner is found to have violated the 

ordinance, state-mandated court costs are added to the amount of the 

violation. 

Thomas J. Seymour felt the sting of the Davenport ATE ordinance 

on April 28, 2006. He received a citation alleging that his vehicle 
5

traveled forty-nine miles per hour in a thirty-five mile-per-hour zone on 

March 17, 2006. Seymour contested the citation. 

Seymour’s case was tried to a magistrate on a stipulated record. 

Seymour claimed that the ATE ordinance violated due process by shifting 

the burden of proof to the defendant to disprove a citation, by depriving a 

defendant of the presumption of innocence, by changing the burden of 

proof from the reasonable doubt standard to the lesser standard of clear, 

satisfactory, and convincing evidence, and by shifting liability to vehicle 

owners, not drivers. Seymour also claimed that the Davenport ATE 

ordinance was invalid because it was preempted by traffic regulations 

and enforcement mechanisms contained in Iowa Code chapter 321 and 

sections 364.22(5)(b), 805.6, and 805.8A. 

The magistrate rejected all of Seymour’s claims, found that he 

violated the ordinance, and entered judgment against him. Seymour 

appealed to the district court, which affirmed the judgment. 

We granted Seymour’s application for discretionary review. While 

Seymour raised constitutional challenges based on due process in the 

lower courts, he has not pressed these claims on appeal and, as a result, 

these issues are not before us. The only issue raised in this appeal is 

whether the Davenport ATE ordinance is preempted because it is 

inconsistent or contrary to Iowa’s statewide traffic laws as cited by 

Seymour. 

II. Standard of Review. 

A trial court’s determination of whether a local ordinance is 

preempted by state law is a matter of statutory construction and is thus 

reviewable for correction of errors at law. State v. Tarbox, 739 N.W.2d 

850, 852 (Iowa 2007). 
6

III. Discussion. 

A. Principles of Preemption Analysis. The central issue in this 

case is whether the provisions of the Davenport ATE ordinance are 

preempted by 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). An overview of the principles of preemption 

analysis provides the framework for resolution of the issue presented on 

appeal. 

In 1968, the Iowa Constitution was amended to provide municipal 

governments with limited powers of home rule. Iowa Const. art. III, 

§ 38A. The home rule amendment established what we have referred to 

as legislative home rule. Berent v. City of Iowa City, 738 N.W.2d 193, 

196 (Iowa 2007). Under legislative home rule, the legislature retains the 

unfettered power to prohibit a municipality from exercising police 

powers, even over matters traditionally thought to involve local affairs. 

Conversely, as long as an exercise of police power over local affairs is not 

“inconsistent with the laws of the general assembly,” municipalities may 

act without express legislative approval or authorization. Iowa Const. 

art. III, § 38A. City authorities are no longer frightened by Dillon’s 

ghost.1 

 In order to determine whether municipal action is permitted or 

prohibited by the legislature, courts have developed the doctrine of 

preemption. The general thrust of the preemption doctrine in the context 

of local affairs is that municipalities cannot act if the legislature has 

 1In 1868, the Chief Justice of the Iowa Supreme Court, John F. Dillon, declared 

that municipalities were creatures of the legislature and had only those powers 

expressly granted by the legislature. City of Clinton v. Cedar Rapids & Mo. River R.R.,

24 Iowa 455, 475 (1868). Later this rule became known as the Dillon Rule. 
7

directed otherwise. When exercised, legislative power trumps the power 

of local authorities. 

 We have recognized three types of preemption. The first type, 

generally known as express preemption, applies where the legislature 

has specifically prohibited local action in a given area. Goodell v. 

Humboldt County, 575 N.W.2d 486, 492–93 (Iowa 1998); Chelsea Theater 

Corp. v. City of Burlington, 258 N.W.2d 372, 373 (Iowa 1977). In cases 

involving express preemption, the specific language used by the 

legislature ordinarily provides the courts with the tools necessary to 

resolve any remaining marginal or mechanical problems in statutory 

interpretation. 

 Where the legislature seeks to prohibit municipal action in a 

particular subject area, express preemption offers the highest degree of 

certainty with the added benefit of discouraging unseemly internecine 

power struggles between state and local governments. Express 

preemption is most consistent with the notion that “[l]imitations on a 

municipality’s power over local affairs are not implied; they must be 

imposed by the legislature.” City of Des Moines v. Gruen, 457 N.W.2d 

340, 343 (Iowa 1990). 

Nonetheless, this court has found that express preemption alone is 

not a sufficient tool to vindicate legislative intent in all circumstances. In 

order to ensure maximum loyalty to legislative intent, this court has 

developed the residual doctrine of implied preemption, notwithstanding 

language in our cases disapproving of implied limitations on municipal 

power. Implied preemption arises in two situations where the intent of 

the legislature to preempt is apparent even though the legislature did not 

expressly preempt in unambiguous language. 
8

 Implied preemption occurs where an ordinance prohibits an act 

permitted by statute, or permits an act prohibited by statute. Goodell, 

575 N.W.2d at 493; Gruen, 457 N.W.2d at 342. Under these 

circumstances, although there is no express preemption, the statute on 

its face contains a command or mandate that by its very nature is 

preemptory. The theory of this branch of implied preemption is that even 

though an ordinance may not be expressly preempted by the legislature, 

the ordinance cannot exist harmoniously with a state statute because 

the ordinance is diametrically in opposition to it. The exclamation point 

of an express preemption provision is simply redundant in light of the 

mandatory legislative expression. Although we used the label “implied 

preemption” to distinguish it from express preemption, this type of 

preemption is perhaps more accurately described as “conflict 

preemption.” See, e.g., Colacicco v. Apotex Inc., 521 F.3d 253, 261 (3d 

Cir. 2008); Mars Emergency Med. Servs., Inc. v. Twp. of Adams, 740 A.2d 

193, 195 (Pa. 1999). 

Although implied preemption of the conflict variety occurs 

frequently, the legal standard for its application is demanding. In order 

to qualify for this branch of implied preemption, a local law must be 

“irreconcilable” with state law. Gruen, 457 N.W.2d at 342. Further, our 

cases teach that, if possible, we are to “interpret the state law in such a 

manner as to render it harmonious with the ordinance.” Id.; see also 

Iowa Grocery Indus. Ass’n v. City of Des Moines, 712 N.W.2d 675, 680 

(Iowa 2006); City of Iowa City v. Westinghouse Learning Corp., 264 

N.W.2d 771, 773 (Iowa 1978). In applying implied preemption analysis, 

we presume that the municipal ordinance is valid. Iowa Grocery, 712 

N.W.2d at 680. The cumulative result of these principles is that for 
9

implied preemption to occur based on conflict with state law, the conflict 

must be obvious, unavoidable, and not a matter of reasonable debate. 

 A second form of implied preemption occurs when the legislature 

has so covered a subject by statute as to demonstrate a legislative intent 

that regulation in the field is preempted by state law. Like implied 

preemption based on conflict, the test for field preemption is stringent. 

Extensive regulation of area alone is not sufficient. Goodell, 575 N.W.2d 

at 493; City of Council Bluffs v. Cain, 342 N.W.2d 810, 812 (Iowa 1983). 

In order to invoke the doctrine of field preemption, there must be some 

clear expression of legislative intent to preempt a field from regulation by 

local authorities, or a statement of the legislature’s desire to have 

uniform regulations statewide. Goodell, 575 N.W.2d at 499–500; City of 

Vinton v. Engledow, 258 Iowa 861, 868, 140 N.W.2d 857, 861 (1966). 

The notion behind field preemption is that the legislature need not 

employ “magic words” to close the door on municipal authority. Yet, 

courts are not to speculate on legislative intent, even in a highly 

regulated field. There must be persuasive concrete evidence of an intent 

to preempt the field in the language that the legislature actually chose to 

employ. Goodell, 575 N.W.2d at 493. 

 Field preemption is a narrow doctrine that cannot be enlarged by 

judicial policy preferences. In determining the applicability of field 

preemption, this court does not entertain arguments that statewide 

regulation is preferable to local regulation or vice versa, but focuses 

solely on legislative intent as demonstrated through the language and 

structure of a statute. Id. at 498–99. 

In this case, the parties agree that the legislature has not expressly 

preempted the Davenport ATE ordinance. The only question is whether 
10

one of the branches of implied preemption applies in light of the 

statutory provisions cited by Seymour. 

B. Application of Preemption Principles to the ATE Ordinance. 

1. Relevant statutory provisions. Entitled “Motor Vehicles and the 

Law of the Road,” Iowa Code chapter 321 contains 562 sections. Among 

other things, Iowa Code chapter 321 establishes substantive standards 

related to speeding, obeying traffic signals, and establishes mechanisms 

of enforcement. Iowa Code §§ 321.285, 321.256. Infractions for 

speeding and violating traffic signals are generally considered simple 

misdemeanors. Id. § 321.482. Convictions for violation of these criminal 

statutes are reported to the IDOT and can result in suspension or 

revocation of driving privileges where the driver has committed multiple 

offenses within a prescribed statutory period. Id. §§ 321.201–.215. 

Of central concern to the preemption challenge in this case is Iowa 

Code section 321.235, which provides: 

The provisions of this chapter shall be applicable and 

uniform throughout this state and in all political subdivisions 

and municipalities therein and no local authority shall enact 

or enforce any rule or regulation in conflict with the 

provisions of this chapter unless expressly authorized 

herein. Local authorities may, however, adopt additional 

traffic regulations which are not in conflict with the provisions 

of this chapter. 

Id. § 321.235 (emphasis added). Iowa Code section 321.235 is a twofaced statute. The Janus-like code provision declares that the provisions 

of the chapter are “applicable and uniform” throughout the state, but 

then expressly authorizes local governments to enact “additional traffic 

regulations” that are “not in conflict” with the provisions of the chapter. 

The next provision of the code adds additional relevant language. 

Iowa Code section 321.236 provides: 
11

Local authorities shall have no power to enact, enforce, or 

maintain any ordinance, rule or regulation in any way in 

conflict with, contrary to or inconsistent with the provisions of 

this chapter, and no such ordinance, rule or regulation of 

said local authorities heretofore or hereafter enacted shall 

have any force or effect, however the provisions of this 

chapter shall not be deemed to prevent local authorities with 

respect to streets and highways under their jurisdiction and 

within the reasonable exercise of police power from: [list of 

fourteen exceptions]. 

Id. § 321.236 (emphasis added). The fourteen listed exceptions in this 

section give municipalities or rural residence districts the power to 

prescribe standards of conduct. Under the listed exceptions, 

municipalities are expressly authorized to regulate conduct related to the 

parking of vehicles, processions or assemblages on highway, traffic flow 

on highways locally designated for one-way traffic, speed in public parks, 

designation of highways as a through highway requiring intersecting 

traffic to yield, operation of vehicles for hire, use of highways by heavy 

trucks and rubbish vehicles, turning of vehicles at and between 

intersections, the operation of bicycles, speed limits in public alleys, use 

of highways during snow conditions, and the operation of electric 

personal assistive mobility devices. Id. 

The only exception contained in Iowa Code section 321.236 that 

does not expressly authorize limitations of conduct in a specific subject 

area is the penultimate listed exception, which authorizes boards of 

supervisors to create rural residence districts. Id. But even this 

provision indirectly relates to regulation of conduct, as rural residence 

districts created by the board of supervisors are authorized to regulate 

speed and parking of vehicles within the rural residence district 

consistent with the provisions of chapter 321. 

Another provision of Iowa law cited by Seymour is Iowa Code 

section 364.22(5)(b). This provision of Iowa law authorizes municipalities 
12

to establish civil infractions and provide for enforcement. Among other 

things, section 364.22(5)(b) provides that “[t]he city has the burden of 

proof that the municipal infraction occurred and that the defendant 

committed the transaction.” The Code provision also provides that the 

burden of proof for municipal civil infractions is “clear, satisfactory, and 

convincing evidence.” Id.

Seymour also cites Iowa Code sections 805.6 and 805.8A in 

support of his preemption argument. Iowa Code section 805.6 

establishes a uniform citation and complaint for criminal infractions 

related to the rules of the road established in Iowa Code chapter 321. Id.

§ 805.6. Iowa Code section 805.8A establishes a schedule of fines for 

such criminal violations. Id. § 805.8A. 

2. Contentions of the parties. The parties agree that there are a 

number of differences between the provisions of Iowa Code chapter 321 

and the Davenport ATE ordinance. For example, the Davenport ATE 

ordinance creates civil penalties while state law provides only for criminal 

violations; the offense under the Davenport ATE ordinance is against the 

owner of the motor vehicle rather than the driver; violation of the 

Davenport ATE ordinance is not reported to the IDOT and made part of 

the violator’s driving record, whereas violations of state law are so 

reported; the standards of proof in the Davenport ATE ordinance differ 

from those of state violations, which are criminal; the citation form under 

the Davenport ATE ordinance is different from that prescribed for 

criminal violations; and the schedule of municipal civil fines under the 

Davenport ATE ordinance is different from the schedule for violation of 

state criminal law. 

The parties, however, take opposing views of these differences. The 

City maintains that the differences between the Davenport ATE 
13

ordinance and the applicable state laws demonstrate that the Davenport 

ATE ordinance is not contrary to, or inconsistent with state law, but is 

merely supplemental to provisions of the state code. Seymour, on the 

other hand, maintains that the differences powerfully demonstrate 

conflict with state law by creating an entirely new enforcement regime 

that is wholly absent from chapter 321 and related provisions. 

3. Application of preemption principles. A number of our cases 

have explored the question of whether a local ordinance conflicts with 

state law, thereby triggering implied preemption. For example, in Iowa 

Grocery, we invalidated a Des Moines ordinance that allowed the city to 

charge an administrative fee related to liquor licenses and permits in the 

face of a state statute which provided that the Iowa Alcoholic Beverages 

Division, by rule, shall establish the administrative fee to be assessed by 

all local authorities. Iowa Grocery, 712 N.W.2d at 680. Similarly, in 

James Enterprises, Inc. v. City of Ames, 661 N.W.2d 150, 153 (Iowa 

2003), we held that an Ames ordinance which prohibited smoking in 

restaurants during certain hours was preempted by state law which 

allowed designated smoking areas in restaurants. In these cases, local 

ordinances simply could not be reconciled with state law. An additional 

preemption case of older vintage is Engledow, 258 Iowa at 861, 140 

N.W.2d at 857. In that case, we invalidated a local ordinance that 

attempted to change the substantive elements of the crime of reckless 

driving. Engledow, 258 Iowa at 868, 140 N.W.2d at 861. 

The above cases demonstrate that the phrase “irreconcilable” used 

in preemption analysis is a hard-edged term. In order to be 

“irreconcilable,” the conflict must be unresolvable short of choosing one 

enactment over the other. No such bitter choice is presented in this 

case. The Davenport ATE ordinance simply cannot be said to authorize 
14

what the legislature has expressly prohibited, or to prohibit what the 

legislature has authorized. Nothing in Iowa Code chapter 321, or 

sections 805.6 and 805.8A addresses the question of whether a 

municipality may impose civil penalties on owners of vehicles through an 

ATE regime. Whether such penalties may be imposed by a municipality 

can only be characterized as a question which the legislature did not 

address. 

Using the principles established by our case law regarding implied 

conflict preemption, namely, that a local ordinance is not impliedly 

preempted unless it is “irreconcilable,” that every effort should be made 

to harmonize a local ordinance with a state statute, and that implied 

preemption only applies where a local ordinance prohibits what a state 

statute allows or allows what a state statute prohibits, we conclude that 

implied conflict preemption simply does not apply in this case. As stated 

by the Ohio Supreme Court in Village of Struthers v. Sokol, 140 N.E. 519, 

521 (Ohio 1923), whether a municipal ordinance is in conflict is not 

determined by the penalties prescribed, but whether the ordinance 

permits or licenses that which the state prohibits or forbids or vice versa. 

See also Chicago & N.W. Transp. Co. v. Kalo Brick & Tile Co., 450 U.S. 

311, 317–18, 101 S. Ct. 1124, 1130, 67 L. Ed. 2d 258, 265 (1981) 

(stating conflict in preemption context is to be assessed by examining the 

activity which the state has attempted to regulate, rather than the 

method used); 56 Am. Jur. 2d Municipal Corporations § 329, at 368–70 

(stating state and local regulation may coexist in identical areas although 

local regulation exacts additional requirements, unless state statute 

limits requirements by prescription). 

We find nothing in Iowa Code section 321.236 to alter our analysis. 

In this provision, the legislature has expressly authorized local 
15

governments to establish rules of conduct related to rules of the road. 

The legislature used no words of limitation in the section. Further, as 

pointed out by the City, the legislature in other sections of the Code has 

authorized municipal action over traffic subjects not contained in section 

321.236. See, e.g., Iowa Code §§ 321.255 (traffic devices), 321.273 

(traffic reports), 321.293 (speed). We do not regard the fourteen 

categories in Iowa Code section 321.236, therefore, as exclusive or as 

overriding the general command of Iowa Code section 321.235 that 

authorizes additional traffic regulations where they are not contrary to or 

inconsistent with state law. 

We also reject Seymour’s claim that the Davenport ATE ordinance 

conflicts with Iowa Code section 364.22(5)(b). We certainly agree that 

under this statutory provision, the municipality has the burden of 

proving all elements of a civil infraction by clear and convincing 

evidence.2 But there is nothing in the Davenport ATE ordinance that is 

inconsistent with Iowa Code section 364.22(5)(b) that requires us to hold 

that the Davenport ATE ordinance is preempted. There is simply no 

provision in the Davenport ATE ordinance that alters the requirement 

that the City prove, by a clear, satisfactory, and convincing 

preponderance of evidence, that the defendant was the registered owner 

of the vehicle photographed violating the ATE ordinance. Seymour may 

not like the substance of the ordinance, which potentially imposes 

vicarious liability for traffic violations upon registered owners, but such a 

substantive challenge is irrelevant to the narrow question at hand, 

 2The Davenport ordinance creates civil penalties and, as a result, the “clear, 

satisfactory, and convincing” standard of Iowa Code section 364.22(5)(b) is not 

inconsistent with the reasonable doubt standard established in our case law for 

criminal violations. City of Des Moines v. Rosenberg, 243 Iowa 262, 272–73, 51 N.W.2d 

450, 456 (1952). 
16

namely, whether the Davenport ATE ordinance is inconsistent with state 

law. 

The remaining question is whether the traffic regulations and 

enforcement mechanisms of Iowa Code chapter 321 are designed to 

preempt the field in a fashion that prohibits municipalities from enacting 

supplementary traffic enforcement ordinances such as the Davenport 

ATE ordinance. The legislative language related to uniform enforcement 

of traffic laws in Iowa Code section 321.235 suggests that field 

preemption may be at work. In addition, the length, breadth, and 

comprehensiveness of Iowa Code chapter 321 offers support for the 

application of field preemption to the Davenport ATE ordinance. 

Yet, the introductory language in Iowa Code section 321.235 

regarding uniformity must be read in tandem with the subsequent 

language expressly vesting power in municipalities to enact additional 

traffic regulations that are not “inconsistent” with Iowa Code chapter 

321. This subsequent language eliminates any basis for field preemption 

because the legislature has expressly authorized municipalities to enact 

local ordinances regarding the subject matter—namely, traffic 

regulations—that are “not inconsistent with” the Code. Indeed, when it 

comes to traffic regulations, the legislature has expressly declined to 

preempt the field, so long as conflicts are not present. Iowa Code 

§ 321.235; see, e.g., Big Creek Lumber Co. v. County of Santa Cruz, 136 

P.3d 821, 833 (Cal. 2006) (finding that general legislative statements of 

intent to establish comprehensive regulation do not preempt field where 

statute also expressly authorizes local action); Dep’t of Licenses & 

Inspections, Bd. of License & Inspection Review v. Weber, 147 A.2d 326, 

328 (Pa. 1959) (holding legislative language allowing municipality to 

adopt appropriate ordinances not inconsistent with act demonstrates 
17

lack of field preemption); Brown v. City of Yakima, 807 P.2d 353, 355 

(Wash. 1991) (noting where statute expressly confers some measure of 

concurrent jurisdiction, field preemption does not apply). 

Although not articulated as such by the parties, we believe the nub 

of both the conflict and field preemption issues is whether the doctrine of 

expressio unius est exclusio alterius applies to defeat the Davenport ATE 

ordinance. Under this rule of statutory interpretation, a provision that a 

statutory mandate be carried out in one way implies a prohibition 

against doing it another way. See Norman J. Singer, Statutes and 

Statutory Construction ch. 46 (6th ed. 2000). Arguably, by providing a 

criminal penalty for speeding and red light violations, the legislature 

should be deemed to have rejected alternate remedies such as civil 

penalties. 

The issue here, however, is not whether the state legislature has 

authorized state authorities to establish an ATE system to enforce red 

light and speeding laws. This case involves the materially different 

question of whether state law prohibits municipal authorities from 

creating such a system. Unless the long-deceased Dillon Rule is 

resurrected, the notion that the mere failure of the legislature to 

authorize invalidates municipal action is without merit. Under our case 

law, the state statute and the municipal action must be irreconcilable. 

The fact that state law does not authorize the state to enforce its statute 

through certain remedial options does not mean that it forbids 

municipalities from the same course of action. In the context of statelocal preemption, the silence of the legislature is not prohibitory but 

permissive. See Cameron v. City of Waco, 8 S.W.2d 249, 254 (Tex. Civ. 

App. 1928) (holding that rule of expressio unius est exclusio alterius does 

not apply in determining scope of municipal powers under home rule). 
18

We recognize that the Colorado and Minnesota Supreme Courts 

have held that automated traffic enforcement regimes were preempted by 

state traffic laws. City of Commerce City v. State, 40 P.3d 1273, 1285 

(Colo. 2002); State v. Kuhlman, 729 N.W.2d 577, 584 (Minn. 2007). On 

the other hand, the Supreme Court of Ohio has reached an opposite 

conclusion. Mendenhall v. City of Akron, 881 N.E.2d 255, 265 (Ohio 

2008). We have reviewed the Colorado and Minnesota cases and find 

nothing to dissuade us from our approach, which is dictated by wellestablished Iowa case law. 

In reaching our conclusion, we are aware that the desirability of 

ATE ordinances is the subject of contentious political debate. See 

generally Robin Miller, Automated Traffic Enforcement Systems, 26 

A.L.R.6th 179 (2007). Supporters of ATE ordinances may passionately 

assert that the presence of the cameras and speed sensors promote 

public safety and save lives, especially the lives of children, when 

careless driving and road rage are all too common. In contrast, 

opponents may view ATE ordinances as unduly intrusive, unfair, and 

simply amounting to sophisticated speed traps designed to raise funds 

for cash-strapped municipalities by ensnaring unsuspecting car owners 

in a municipal bureaucracy under circumstances where most busy 

people find it preferable to shut up and pay rather than scream and 

fight. 

As we have previously stated, “In construing statutes it is our duty 

to determine legislative intent; the wisdom of the legislation is not our 

concern.” Hines v. Ill. Cent. Gulf R.R., 330 N.W.2d 284, 289 (Iowa 1983). 

As a result, the pros and cons of ATE ordinances have no bearing on the 

narrow legal issue that we are required to decide in this case. Our only 

task is to determine, under established legal principles, the issues that 
19

the parties have presented, specifically, whether the Davenport ATE 

ordinance is preempted by the traffic regulatory and enforcement 

provisions of Iowa Code chapter 321 and sections 364.22(5)(b), 805.6, or 

805.8A. In light of the established cases and the enabling language of 

Iowa Code chapter 321.235, we hold that the doctrine of preemption does 

not apply. Any determination on the merits of the policy arguments is 

not for the court, but the political organs of government influenced by an 

informed electorate. 

We also recognize that a number of statutory and constitutional 

questions have been raised to ATE ordinances that are not presented in 

this appeal. ATE ordinances have been attacked as amounting to an 

unlawful revenue raising measure or as improperly delegating 

government authority to a private vendor. Andrew W. J. Tarr, Picture It: 

Red Light Cameras Abide by the Law of the Land, 80 N.C. L. Rev. 1879, 

1886 (2002) (issue of unlawful revenue raising); see also Leonte v. ACS 

State & Local Solutions, Inc., 19 Cal. Rptr. 3d 879 (Ct. App. 2004) 

(delegation of power). Academic commentators have debated whether 

ATE ordinances violate rights of privacy. See, e.g., Quentin Burrows, 

Scowl Because You’re on Candid Camera: Privacy and Video Surveillance, 

31 Val. U. L. Rev. 1079 (1997); Mary Lehman, Are Red Light Cameras 

Snapping Privacy Rights?, 33 U. Tol. L. Rev. 815 (2002); Steven Tafoya 

Naumchik, Stop! Photographic Enforcement of Red Lights, 30 McGeorge L. 

Rev. 833 (1999). ATE ordinances also have been attacked on due 

process, Fourth Amendment, and equal protection grounds. See, e.g.,

McNeill v. Town of Paradise Valley, 44 Fed. App’x 871 (9th Cir. 2002) 

(Fourth Amendment); Shavitz v. City of High Point, 270 F. Supp. 2d 702 

(M.D.N.C. 2003), vacated on other grounds sub nom. Shavitz v. Guilford 
20

County Bd. of Educ., 100 Fed. App’x 146 (4th Cir. 2004) (equal 

protection); Agomo v. Fenty, 916 A.2d 181 (D.C. 2007) (due process). 

All of the above questions are not raised in this appeal, and we 

consequently express no view on them. This court is not a roving 

commission that offers instinctual legal reactions to interesting issues 

that have not been raised or briefed by the parties and for which the 

record is often entirely inadequate if not completely barren. We decide 

only the concrete issues that were presented, litigated, and preserved in 

this case. 

IV. Conclusion. 

We hold the Davenport ATE ordinance is not preempted by the 

traffic regulations and enforcement mechanisms of Iowa Code chapter 

321 and sections 364.22(5)(b), 805.6, or 805.8A. As a result, the ruling 

of the district court in this matter is affirmed.

AFFIRMED. 

All justices concur except Wiggins, J., who dissents and Baker, J., 

who takes no part. 
21

#33/06–1753, City of Davenport v. Seymour

WIGGINS, Justice (dissenting). 

I dissent. I cannot agree with the majority’s conclusion that the 

legislature’s comprehensive enactment of the traffic regulations and 

enforcement mechanisms contained in chapter 321 of the Iowa Code 

does not preempt Davenport’s Automated Traffic Enforcement ordinance. 

Although the majority recognizes the doctrine of implied preemption, it 

fails to follow our existing case law in its application of the doctrine. 

Chapter 321 includes a uniform law provision. Iowa Code 

§ 321.235 (2007). This provision provides: 

The provisions of this chapter shall be applicable and 

uniform throughout this state and in all political 

subdivisions and municipalities therein and no local 

authority shall enact or enforce any rule or regulation in 

conflict with the provisions of this chapter unless expressly 

authorized herein. Local authorities may, however, adopt 

additional traffic regulations which are not in conflict with 

the provisions of this chapter. 

Id. 

Chapter 321 also limits the power of local authorities to enact an 

ordinance that conflicts with the Code. Id. § 321.236. It states in 

relevant part: 

Local authorities shall have no power to enact, enforce, or 

maintain any ordinance, rule or regulation in any way in 

conflict with, contrary to or inconsistent with the provisions 

of this chapter, and no such ordinance, rule or regulation of 

said local authorities heretofore or hereafter enacted shall 

have any force or effect . . . . 

Id. Although section 321.236 enumerates specific areas where a local 

municipality may regulate, it does not include automatic enforcement 

ordinances. 

 This court has applied these sections on two prior occasions and 

struck down local ordinances that were inconsistent with chapter 321. 
22

Central City v. Eddy, 173 N.W.2d 582, 583–84 (Iowa 1970); City of Vinton 

v. Engledow, 258 Iowa 861, 868, 140 N.W.2d 857, 862 (1966). In City of 

Vinton, the city enacted a local ordinance defining reckless driving as: 

“Every driver of any vehicle upon any street in the city shall 

drive and operate such vehicle in a careful and prudent 

manner and with due regard and precaution for the safety of 

pedestrians, persons, property and other vehicles. No 

person shall operate or drive any vehicle in a manner or at a 

speed greater or other than is reasonable and safe with 

respect to such vehicles, persons, pedestrians or property.” 

City of Vinton, 258 Iowa at 864, 140 N.W.2d at 860 (citation omitted). 

Although a prior state statute defined reckless driving in this manner, 

the present state statute only allowed a finding of reckless driving when 

“[a]ny person [ ]drives any vehicle in such manner as to indicate either a 

willful or a wanton disregard for the safety of persons or property . . . .” 

Id. at 865, 140 N.W.2d at 860. 

There this court recognized the state of mind of the violator for 

committing the offense of reckless driving was lower under the city 

ordinance than the state statute. The city ordinance only required a 

finding of negligence to hold the driver culpable, while the state 

ordinance required a finding of “either a willful or a wanton disregard for 

the safety of persons or property.” Id. In analyzing the city ordinance, 

the court first determined that this type of regulation was not contained 

as an exception to section 321.236. Id. at 865–66, 140 N.W.2d at 860–

61. 

Next, the court considered whether the city ordinance was 

consistent with the state statute, as required by section 321.235. The 

test set out by our court to determine whether a statute is valid under 

sections 321.235 and 321.236 is that “[a] city ordinance cannot be 

allowed to change the statutory definition either by enlargement or 
23

diminution.” Id. at 866, 140 N.W.2d at 861. The court went on to say, 

“ ‘[T]he test of the validity of a statute or ordinance is not what has been 

done under it but what may be done by its authority.’ ” Id. (quoting 

Chicago, Rock Island & Pac. R.R. v. Liddle, 253 Iowa 402, 409, 112 

N.W.2d 852, 856 (1962)). 

In applying these principles, the court found the difference 

between the state of mind needed to hold violators liable under the state 

and city laws destroyed the uniformity required by sections 321.235 and 

321.236. Id. The state of mind needed for holding a person culpable for 

reckless driving is a matter of legislative policy. Id. Because the laws in 

Vinton were not consistent with the rules of the road enforceable in other 

parts of the state, this court held the Vinton ordinance invalid. Id. 

In 1970 the court was asked to revisit a similar issue. Central 

City, 173 N.W.2d at 583–85. There the city held drivers culpable for 

careless or negligent driving on public streets, alleys, and highways. Id. 

at 583. Our court recognized that the legislature only held a driver 

culpable for driving with either a willful or a wanton disregard for the 

safety of persons or property. Id. at 584. Thus, the city’s ordinance 

holding a driver culpable for negligent driving was inconsistent with state 

law. Id. Accordingly, the ordinance was invalid. Id. 

Applying established law to the facts of this case can only lead to 

one conclusion—Davenport’s Automated Traffic Enforcement ordinance 

violates sections 321.235 and 321.236. No one argues the ordinance is 

allowed under an enumerated exception to section 321.236. Thus, we 

must determine whether the Davenport ordinance is inconsistent with 

chapter 321. 

The legislature has defined when an owner of a vehicle may be 

culpable for a violation of chapter 321. Iowa Code § 321.484. Under 
24

chapter 321, an owner can only be culpable for a driver’s moving 

violation if the owner of any vehicle requires, or knowingly permits the 

operation of such vehicle upon a highway in any manner contrary to the 

law. Id. Under Davenport’s ordinance, an owner is strictly liable for the 

actions of a person driving the owner’s vehicle. By requiring a lesser 

state of mind for an owner to be culpable of the same offense, the 

Davenport ordinance is inconsistent with the stated legislative policy 

regarding the culpability of owners under chapter 321. 

 It may be asserted that because the violation of the ordinance is a 

civil infraction, it is not inconsistent with chapter 321. I cannot agree 

with this premise. 

In Illinois several municipalities passed local ordinances allowing 

traffic offenders to pay a civil settlement fee in lieu of court adjudication. 

People ex rel. Ryan v. Vill. of Hanover Park, 724 N.E.2d 132, 135 (Ill. App. 

Ct. 1999). Like Davenport’s ordinance, a traffic violator in these 

municipalities would pay a fine to the municipality and the violation 

would not be reported to the state. Section 11-207, chapter 11 of the 

Illinois Code contains the same language as section 321.235 of the Iowa 

Code. Id. at 139. 

The Illinois Appellate Court found this statute violated the 

uniformity requirement of traffic laws contained in section 11-207 of 

chapter 11 for two reasons. Id. at 143–44. First, the ordinance allows 

certain moving violations to be adjudicated administratively, while the 

Illinois Code requires moving violations to be dealt with judicially. Id. at 

140. Second, by not reporting the violations to the licensing authority, 

the licensing authority cannot exercise its exclusive authority to cancel, 

suspend, or revoke a license. Id. at 141. I agree with the reasoning of 

the Illinois court. 
25

 The Iowa legislature has given Iowa municipalities the power to 

adjudicate parking violations administratively. Iowa Code § 321.236(1). 

The legislature has not given municipalities the authority to adjudicate 

other violations of our traffic code administratively. The judicial system 

must adjudicate all other violations. When law enforcement cites a 

person for a moving violation, the officer must arrest the violator or issue 

a citation. Id. §§ 805.1, 805.6. Court intervention is necessary so the 

violator cannot pay a civil settlement fee in exchange for “an opportunity 

to circumvent the potential consequences of committing the offense, 

namely, a chance to avoid an adjudication [by the court], a finding of 

guilty, and a guilty finding being reported to the [licensing authority].” 

People ex rel. Ryan, 724 N.E.2d at 140. Consequently, for the Davenport 

ordinance to be valid, it must treat its violators as the legislature treats 

violators in other parts of the state. The ordinance can only achieve the 

uniformity required by section 321.235 by adjudicating these moving 

violations judicially. 

 Another problem with the administrative adjudication under the 

Davenport ordinance is its failure to report violators to the department of 

transportation (DOT). The DOT is the sole agency designated by the 

legislature to administer the issuance, suspension, and revocation of a 

driver’s license. Iowa Code § 321.2. In carrying out these duties, the 

DOT has instituted various rules regarding the suspension and 

revocation of a license. Iowa Admin. Code r. 761—615. The action the 

agency takes is dependent on the nature of the violation. See, e.g., id. r. 

761—615.9 (providing for suspension of habitual offenders). The DOT 

has also developed driver improvement programs as an alternative to 

license suspension. Id. r. 761—615.43. 
26

 In order for the DOT to administer the suspension or revocation of 

a driver’s license, it must receive a record of the conviction from the 

court system. Chapter 321 requires the court to advise the DOT of a 

conviction. Iowa Code § 321.491. The Davenport ordinance does not. 

The legislative intent behind the enactment of traffic laws is to keep the 

streets and highways of this state safe. One of the most effective means 

of doing that is to reeducate drivers who violate the laws through driver 

improvement programs. If a driver cannot be reeducated, then the DOT 

has the ability to suspend or revoke a license. For this legislative scheme 

to work, the DOT needs to have exclusive control over the 

administration, suspension, and revocation of drivers’ licenses so the 

consequences of committing a violation of chapter 321 remain uniform 

throughout the state. 

 The Davenport ordinance circumvents the DOT’s exclusive control, 

and undermines the goal set forth by the legislature that repeat offenders 

should be kept off our roads. Why would the legislature allow a person 

with five violations under the Davenport ordinance to continue to drive, 

when its stated legislative policy is to prohibit a driver with three moving 

violations in any other part of the state from operating a motor vehicle? 

An unsafe driver in Davenport is an unsafe driver anywhere else in this 

state. By not applying our suspension and revocation laws uniformly, 

our streets and highways become a more dangerous place. 

 I understand Davenport’s desire to decrease the occurrences of 

speeding without the expense of adding more officers for enforcement in 

these tough economic times. I also understand the city’s need to raise 

revenue from new sources. However, I cannot believe an ordinance that 

holds the owner strictly liable and does nothing to remove repeat 

offenders from the road furthers the legislative intent of sections 321.235 
27

and 321.236. Sections 321.235 and 321.236 require the uniform 

applicability of chapter 321 and prohibit municipalities from enacting or 

enforcing any rule or regulation in conflict with the provisions of chapter 

321 unless expressly authorized by the legislature. The uniformity of our 

traffic laws keeps the roads safe for all Iowans. The legislature never 

envisioned that municipalities could raise revenue under the guise of 

traffic law enforcement at the expense of safer highways. 

Accordingly, without specific authorization by the legislature to 

hold owners strictly liable for the acts of a driver, without judicial 

adjudication, and without DOT authority to regulate who should not be 

on the roads, I would hold Davenport’s Automated Traffic Enforcement 

ordinance invalid.