Gen. 81] 81

TRANSPORTATION

LOCAL GOVERNMENT – PREEMPTION – TRAFFIC STOPS –

WHETHER A LOCAL ORDINANCE PROHIBITING LOCAL 

POLICE OFFICERS FROM STOPPING DRIVERS SOLELY FOR 

CERTAIN TRAFFIC OFFENSES WOULD BE PREEMPTED BY 

THE MARYLAND VEHICLE LAW

September 15, 2023

The Honorable Evan Glass

President, Montgomery County Council

The Maryland Vehicle Law—the State statute regulating the 

use of motor vehicles—defines numerous offenses for which police 

officers may issue traffic citations. Motor vehicle offenses can be 

categorized as either “primary” or “secondary.” If a police officer 

observes a primary offense, they may ordinarily stop and cite the 

driver for that offense, without more. But an officer cannot stop a 

driver for a secondary offense standing alone. Instead, an officer 

may issue a citation for a secondary offense only after stopping the 

driver for a separate primary offense. A bill pending before the 

Montgomery County Council—the Safety and Traffic Equity in 

Policing Act, or “STEP Act”—would require Montgomery County 

police officers to treat certain traffic offenses as secondary, even 

though the Maryland Vehicle Law has not defined them as such. 

The STEP Act would also limit Montgomery County officers’ 

ability to ask for consent to search a vehicle, or its occupants, 

during a traffic stop. 

On behalf of the Montgomery County Council, you requested 

an opinion of the Attorney General on whether the Maryland 

Vehicle Law would preempt the STEP Act. In accordance with our 

policy on opinion requests, you provided a memo from the County 

Attorney concluding that the Vehicle Law would preempt the 

provisions of the STEP Act relating to secondary offenses but that 

the STEP Act’s remaining provisions would be valid. You also 

provided a memo from a Legislative Attorney for the Council, 

concluding that the Vehicle Law would not preempt any portion of 

the STEP Act.

In our view, the Vehicle Law would expressly preempt the 

STEP Act’s provision designating certain traffic offenses as 

secondary. Under the Vehicle Law, no local government may 

make or enforce a “local law, ordinance, or regulation on any 

subject covered by the Maryland Vehicle Law.” Md. Code Ann., 
82 [108 Op. Att’y

Transp. (“TR”) § 25-101.1(b)(3). As we will explain, the Maryland 

Vehicle Law covers the subject of which motor vehicle offenses 

are subject to primary enforcement and which are subject to 

secondary enforcement. More specifically, the Vehicle Law 

establishes a general rule that all motor vehicle offenses are subject 

to primary enforcement. It then exempts certain specific offenses 

from that rule, explicitly providing secondary enforcement for 

those specific offenses. Because the Vehicle Law addresses the 

subject of primary versus secondary enforcement, and because the 

General Assembly has chosen to designate certain offenses as 

secondary while leaving the rest as primary, a local law designating 

further offenses as secondary would address a subject that the 

Vehicle Law covers and would thus be preempted. 

Although the Vehicle Law reserves certain powers to local 

governments, none of those reserved powers would authorize the 

secondary-offense provisions of the STEP Act. To be clear, we do 

not question a local government’s general authority to establish 

rules for its own police department. Nor do we address a local 

legislative body’s ability to set enforcement priorities for its local 

police department in areas not subject to express preemption. We 

conclude only that, whatever legislative authority a local 

government otherwise has, the General Assembly has overridden 

that authority for subjects the Vehicle Law addresses, including the 

subject of which motor vehicle offenses are secondary.

On the other hand, the Vehicle Law would not preempt the 

STEP Act’s remaining provisions. In particular, the Vehicle Law 

would not preempt the STEP Act’s limitation on consent searches. 

That provision would preclude an officer from requesting consent 

to search a vehicle or its occupants during a traffic stop, unless 

there is at least reasonable suspicion to believe a crime has been 

committed. The Maryland Vehicle Law does not address the 

subject of searches during traffic stops. The consent-search 

provision also would not tread on an impliedly preempted field. 

Nor would it conflict with any provision of the Vehicle Law, 

because, again, the Vehicle Law does not address searches. There 

is thus no basis to say that the Vehicle Law would preempt the 

consent-search provision.1

1 We received three sets of comments on this opinion request, 

generally supporting the STEP Act on legal or policy grounds. Angela 

J. Davis et al., Testimony in Support of the Safety and Traffic Equity in 

Policing (STEP) Act—Bill 12-23 (July 5, 2023) (“Davis Comments”); 

Robert Landau, Comments of Robert Landau on the Legality of the 

Montgomery County Bill 12-23 (July 25, 2023); Letter from Chelsea J. 
Gen. 81] 83

I

Background

A. Traffic Stops

Traffic stops are the most common interaction between police 

officers and members of the public in the United States. 

Montgomery County Office of Legislative Oversight, OLO Report 

No. 2021-10, A Study on Reassigning Traffic Enforcement from the 

Montgomery County Police Department to the Montgomery 

County Department of Transportation 5 (2021) (“OLO Report”). 

Maryland law empowers police officers to order a driver to stop by 

means of a “visual or audible signal.” TR § 21-904. Because the 

driver, once pulled over, is not free to leave at will, a traffic stop is 

a “seizure” governed by the Fourth Amendment and Article 26 of 

the Maryland Declaration of Rights.2 See, e.g., Byndloss v. State, 

391 Md. 462, 465 & n.1, 480 (2006). Ordinarily, though, an officer 

can conduct a traffic stop without a warrant if they have reasonable 

suspicion—usually through direct observation—that the driver is 

violating the motor vehicle laws. State v. Williams, 401 Md. 676, 

690-91 (2007). Indeed, the Maryland Vehicle Law affirmatively 

authorizes officers to issue citations for motor vehicle offenses, 

which in turn implies the power to stop the driver. See TR 

§ 26-201. For some specific offenses, though, the authority to 

conduct a stop is limited by statute, as we discuss further below.3

Crawford, Esq., to Hon. Anthony G. Brown, Attorney General (Aug. 10, 

2023). We thank the commenters for their views, and we have 

considered their comments in developing the analysis below.

2 Article 26 provides: “That all warrants, without oath or affirmation, 

to search suspected places, or to seize any person or property, are 

grievous and oppressive; and all general warrants to search suspected 

places, or to apprehend suspected persons, without naming or describing 

the place, or the person in special, are illegal, and ought not to be 

granted.” Md. Decl. Rights Art. 26. The scope of Article 26’s protection 

against searches and seizures is generally the same as the Fourth 

Amendment’s. See, e.g., King v. State, 434 Md. 472, 482-83 (2013).

3 While the default rule is that motor vehicle offenses in Maryland are 

misdemeanors, see TR § 27-101, some are felonies, e.g., TR

§ 20-102(c)(3) (leaving the scene of an accident when the defendant 

knew or reasonably should have known that the accident resulted in 

serious bodily injury or death), and others are subject only to civil 

penalties, e.g., TR § 21-1414(c) (failing to pay a toll assessed by a video 

monitoring system). We do not consider the question of when an officer 

can stop a driver who has committed only a civil offense.
84 [108 Op. Att’y

Constitutional limits also control what the officer can do once 

the driver has been stopped. A stop generally cannot last longer 

than necessary to accomplish its original purpose, which is 

normally to investigate the traffic violation and issue a warning or 

citation if appropriate. See, e.g., Ferris v. State, 355 Md. 356, 372 

(1999). But an officer may continue to detain the vehicle if the 

officer has reasonable suspicion that some other criminal activity 

is afoot. Id. And an officer may also request consent to search the 

vehicle or its occupants. See id.; Scott v. State, 247 Md. App. 114, 

132, 150-52 (2020). A warrantless search based on consent is 

ordinarily valid with or without reasonable suspicion or probable 

cause, even in the context of a traffic stop. See State v. Green, 375 

Md. 595, 609-10 (2003); Gamble v. State, 318 Md. 120, 123-24 

(1989). But see Md. Code Ann., Crim. Proc. (“CP”) § 1-211(c) 

(providing that evidence obtained through certain cannabis-related 

searches is inadmissible even if obtained with consent).4

Traffic stops serve an important public safety function. They 

enable officers to deter and stop dangerous driving, which in turn 

helps reduce crashes and injuries. OLO Report at i, 5. But 

advocates and researchers have raised concerns about racial 

disparities in the frequency of traffic stops, especially in the 

frequency of traffic stops where the officer’s primary motivation is 

to search for evidence of other crimes. Id. at 76-77. Such 

“investigatory” stops have been upheld against Fourth Amendment 

challenge by the United States Supreme Court, see Whren v. United 

States, 517 U.S. 806, 813 (1996), but are often criticized as 

“pretextual,” see, e.g., Wayne R. LaFave, The “Routine Traffic 

Stop” from Start to Finish: Too Much “Routine,” Not Enough 

Fourth Amendment, 102 Mich. L. Rev. 1843, 1852-61, 1902-03 

(2004); Snyder v. State, No. 1127, Sept. Term, 2021, 2023 WL 

1497289, *8-*10 (Md. App. Ct. Feb. 3, 2023) (unreported) 

(Friedman, J., concurring) (criticizing Whren and arguing that the 

Supreme Court of Maryland should adopt a rule against 

“pretextual” stops under Article 26 of the Declaration of Rights).5 

4 Other exceptions to the warrant requirement, such as the “plain 

view” exception or the “automobile exception,” may apply in the context 

of a traffic stop. See Livingston v. State, 317 Md. 408, 412-13 (1989); 

107 Opinions of the Attorney General 153, 162-63, 166 n.20 (2022). 

However, because the STEP Act does not address these exceptions, we 

need not discuss them here.

5 As the law professors’ comments to our Office put it, “some police 

officers use traffic stops to racially profile black and brown drivers. 

They use traffic stops as a pretext for stopping these drivers so they can 

look inside their cars and ask for consent to search, even though they 
Gen. 81] 85

Research indicates that Black and Latino drivers are stopped at 

higher rates than white drivers for “minor” or “technical” offenses 

(i.e., those that do not directly threaten a crash or injury). OLO 

Report at 76-77 & nn.4-6 (citing social science literature). And 

such “technical” violations are the most common basis for 

“investigatory” stops. See id. The concern, then, is that police 

freedom to conduct traffic stops for “technical” violations is a 

major source of racial disparity in traffic enforcement.

In Maryland, 125 law enforcement agencies conducted more 

than 482,000 traffic stops in 2021. See Governor’s Office of Crime 

Prevention, Youth, and Victim Services, Race-Based Traffic Stop 

Data Dashboard, https://goccp.maryland.gov/data-dashboards/trafficstop-data-dashboard/ (enter “2021” for “Year”) (last visited Sept. 

12, 2023) (“Data Dashboard”). There are several law enforcement 

agencies with the power to make traffic stops in Montgomery 

County (or at least parts of the County), including the Montgomery 

County Police Department (“MCPD”), the Maryland State Police, 

the Montgomery County Sheriff’s Office, and municipal police 

departments. See id.; OLO Report at 13 n.17. Because some of 

these agencies are created by local law as arms of local 

government, the question arises whether local governments can 

regulate the ability of their police departments to make traffic stops. 

The answer to that question depends on the preemptive scope of 

the Maryland Vehicle Law.

B. The Maryland Vehicle Law

The Maryland Vehicle Law (Titles 11 through 27 of the 

Transportation Article, Maryland Code) regulates motor vehicle 

ownership and operation in the State. Its purpose is to ensure “that 

traffic shall move smoothly, expeditiously and safely [and] that no 

legitimate user of the highway . . . shall be killed, injured or 

frustrated in such use by the improper behavior of others.” 

Uniform Vehicle Code vii (National Comm. on Unif. Traffic Laws 

& Ordinances 1968 rev.); see also Committee to Study Revision of 

the Motor Vehicle Laws, Proposed Revision of the Motor Vehicle 

Laws of the State of Maryland iii (1968) (explaining that most 

recent substantive revision of the Vehicle Law was based on the 

Uniform Vehicle Code).

The Vehicle Law expressly limits the lawmaking authority of 

local governments. “Except as otherwise expressly authorized . . . 

have no legal grounds to suspect them of criminal behavior.” Davis 

Comments at 2.
86 [108 Op. Att’y

no local authority or political subdivision of this State may . . . 

make or enforce any local law, ordinance, or regulation on any 

subject covered by the Maryland Vehicle Law.” TR § 25-101.1(b)(3). 

The statute then reiterates that “[t]he provisions of the Maryland 

Vehicle Law prevail over all local legislation and regulation on any 

subject with which the Maryland Vehicle Law deals.” TR 

§ 25-101.1(c)(1). At the same time, the Vehicle Law grants certain 

express powers to local governments, including the power of 

“[r]egulating traffic by means of police officers or traffic control 

devices,” TR § 25-102(a)(2), and of “regulating or prohibiting the 

stopping, standing, or parking of vehicles,” TR § 25-102(a)(1).

The General Assembly enacted the earliest precursor of the 

Vehicle Law in 1904, just a few years after the first automobiles 

appeared in Maryland. 1904 Md. Laws, ch. 518; see also Carriage 

Without Horses, Balt. Sun, Dec. 20, 1898, at 10 (announcing the 

expected arrival in February 1899 of the first “horseless carriage” 

in Baltimore). As cars proliferated, the rules governing them grew 

more complex, and legislators became more interested in ensuring 

statewide uniformity. In 1916, the General Assembly prohibited 

local governments from establishing their own speed limits, 

licensing or registration requirements, or motor vehicle taxes. 1916 

Md. Laws, ch. 687. But State authorities soon decided stronger 

preemption was needed. In 1927, the General Assembly expressly 

preempted local lawmaking on any subject covered by the State 

vehicle law.6 That preemption provision remains in effect, with 

6 As originally enacted, the preemption provision read: 

Except to the extent that they may be specifically 

authorized by other provisions of this sub-title 

[Article 56, Subtitle “Motor Vehicles”], no city, 

county or other political sub-division of this State 

shall have the right to make or enforce any 

ordinance or regulation upon any subject for 

which provision is made in this sub-title. The 

provisions of this sub-title (except as herein 

otherwise specifically provided), are intended to 

be exclusive of all local and municipal legislation 

or regulations, upon the various subjects with 

which this sub-title purports to deal, and all public 

local laws, ordinances and regulations, 

inconsistent or identical therewith, or similar or 

equivalent thereto, are hereby repealed; and the 

charters of all municipal corporations of this State 

are hereby modified so as to prohibit such 

corporations from making or enforcing any 
Gen. 81] 87

only limited changes, as today’s TR § 25-101.1. Former Attorney 

General Thomas H. Robinson, who drafted the preemption statute, 

explained that it was intended to “remove all doubt . . . and to make 

it clear that the provisions of the general motor vehicle law were 

exclusive of all public local laws and municipal ordinances and 

regulations, covering the same subject matter.” 14 Opinions of the 

Attorney General 210, 214 (1929).

 

The General Assembly apparently had second thoughts about 

the preemption provision’s breadth. In 1929, it amended the 

preemption language to recognize local governments’ authority to 

adopt “reasonable traffic regulations” notwithstanding the State 

law. 1929 Md. Laws, ch. 319. But in 1943, as part of a general 

substantive revision of the Vehicle Law, the General Assembly 

repealed that exception, restoring the preemption provision to its 

1927 scope. 1943 Md. Laws, ch. 1007. 

There have been two comprehensive revisions of the Vehicle 

Law. Each has drawn on the Uniform Vehicle Code developed by 

the National Committee on Uniform Traffic Laws and Ordinances. 

The first revision, in 1943, aimed at “promoting greater uniformity 

and thereby achieving greater safety.” Report of the Commission 

on the Revision of the State Motor Vehicle Laws 8 (1942) (“1942 

Report”). As mentioned, this revision (among other changes) 

repealed the authority of local governments to adopt “reasonable 

traffic regulations.” At the same time, the General Assembly 

codified a list of express powers of local governments, drawn from 

the Uniform Code. These included the power of “[r]egulating 

traffic by means of peace officers or traffic control devices” and 

“[r]egulating the standing or parking of vehicles.” Compare 1943 

Md. Laws, ch. 1007 (enacting Art. 66 1⁄2, § 135), with Uniform 

Vehicle Code, Uniform Act Regulating Traffic on Highways § 28, 

at 5 (Nat’l Conference on Street & Highway Safety 1938 rev.); see 

also 1942 Report at 2. 

The second revision, in 1970, made no substantive changes 

either to the preemption provision or to the two express powers 

mentioned above. 1970 Md. Laws, ch. 534 (enacting Art. 66 1⁄2, 

§§ 15-101, 15-102); see also Maryland Dep’t of Motor Vehicles, 

Motor Vehicle Laws Revision 495-98 (1969) (comparing newly 

ordinance or regulations in violation of this 

section.

1927 Md. Laws, ch. 520, § 3 (codified as Art. 56, § 171-A).
88 [108 Op. Att’y

revised sections to prior law).7 Finally, a non-substantive code 

revision in 1977 adopted the current section numbering, codifying 

the preemption provision at TR § 25-101.1 and the list of local 

powers at TR § 25-102. 1977 Md. Laws, ch. 14.

C. Primary and Secondary Offenses

As discussed above, officers ordinarily have broad authority 

to stop drivers for motor vehicle violations. Williams, 401 Md. at 

690-91. And a driver’s consent to a search can be voluntary even 

if obtained during a traffic stop. Green, 375 Md. at 614-15. But 

legislators can impose stricter limits on searches and seizures—

including traffic stops—than the Constitution (State or federal) 

requires. See 107 Opinions of the Attorney General 153, 189-90 

(2022) (concluding that, even if vehicle searches based on the odor 

of cannabis would be constitutional, the General Assembly could 

prohibit such searches); see also CP § 1-211 (limiting law 

enforcement officers’ authority to conduct stops and searches 

based solely on the odor of cannabis).

One potential statutory limit on officers’ authority to stop 

vehicles is the designation of certain motor vehicle offenses as 

“secondary.” A secondary violation is conduct that, although 

unlawful, does not—by itself—allow an officer to initiate a traffic 

stop or issue a citation. See, e.g., Christi Schofield, Comment, 

Texas, Are We There Yet?, 15 Tex. Tech Admin. L.J. 399, 410 

(2014) (discussing status of texting while driving as a primary or 

secondary offense). The officer may only issue a citation for a 

secondary offense if they have already stopped the driver for a 

“primary offense” (meaning any offense that has not been 

designated as secondary). Id.

The Maryland Vehicle Law expressly designates certain 

traffic offenses as secondary offenses. For example, the Vehicle 

Law prohibits driving “with any object, material, or obstruction 

hanging from the rearview mirror that interferes with the clear view 

of the driver through the windshield.” TR § 21-1104(c)(3). But a 

7 The 1970 version retained prior language providing local 

governments power to “[r]egulat[e] the standing or parking of vehicles” 

even though the most recent Uniform Vehicle Code revision referred to 

“[r]egulating or prohibiting stopping, standing or parking.” Uniform 

Vehicle Code § 15-102(a)(1) (1968 rev.) (emphasis added). The word 

“stopping” was later added to the Maryland provision as part of nonsubstantive code revision in 1977; the Revisor’s Note stated that its 

omission had been an “oversight.” 1977 Md. Laws, ch. 14 (Revisor’s 

Note to TR § 25-102).
Gen. 81] 89

“police officer may enforce this [prohibition] only as a secondary 

action when the police officer detains a driver of a motor vehicle 

for a suspected violation of another provision of the Code.” TR 

§ 21-1104(c)(3)(ii). The Vehicle Law also establishes secondaryoffense status for driving with a partly obscured license plate, TR 

§ 13-411(c), violating passenger restrictions on provisional license 

holders, TR § 21-1123, driving without headlights in rainy 

conditions, TR § 22-201.2, and failure to wear a seatbelt by a 

passenger over 16 in the back seat, TR § 22-412.3(c)(3). All of 

these remain traffic violations, but they do not, standing alone, 

provide a basis for an officer to stop a vehicle or cite a driver.

D. The STEP Act

The STEP Act is a bill pending before the Montgomery 

County Council. The bill seeks to reduce racial disparities in traffic 

enforcement while promoting traffic safety. Bill No. 12-23, 

Montgomery County Council (Feb. 28, 2023) (“STEP Act”) 

(proposed Montgomery County Code § 35-27(a)). The STEP Act 

would make two major changes to MCPD officers’ traffic 

enforcement authority. First, it would designate several offenses 

under the Motor Vehicle Law as secondary offenses, beyond those 

already identified as secondary by the Vehicle Law itself. Id.

(proposed § 35-27(c), (d)). Second, it would limit the ability of 

MCPD officers to request consent to search during traffic stops. Id.

(proposed § 35-27(e)). The bill would also impose reporting 

requirements and prohibit collective bargaining over the subjects it 

covers. Id. (proposed §§ 33-80, 35-28). There is an express 

severability clause. Id. (proposed § 35-29).

The secondary-offense provisions are found in proposed new 

sections § 35-27(c) and (d) of the Montgomery County Code. The 

STEP Act would designate as a secondary offense: Any offense 

under Title 13 of the Transportation Article, relating to vehicle 

titles, registration, and license plates; any offense under Title 16, 

relating to driver’s licenses; any offense under Title 17, relating to 

required insurance; fourteen enumerated provisions of Title 22, 

relating to vehicle equipment;8and §§ 21-203(c) and 21-503, 

8 Specifically: driving a vehicle in an unsafe condition or with 

improper equipment (§ 22-101(a)); driving without headlights in lowvisibility conditions (§ 22-201.1); driving without headlights while 

operating windshield wipers due to low visibility (§ 22-201.2) (which is 

already a secondary offense under State law); driving a vehicle that does 

not have at least two headlamps (§§ 22-203(b) and 22-226(a)); driving a 

vehicle that does not have the rear license plate illuminated 
90 [108 Op. Att’y

which prohibit jaywalking (collectively, the “covered provisions”). 

STEP Act (proposed § 35-27(c)). The covered provisions together 

accounted for around 10–20% of all traffic stops by the MCPD in 

2021.9 If the STEP Act were enacted, an MCPD officer could not 

“stop or detain a person operating a motor vehicle, solely for a 

suspected violation of” one of the covered provisions. Id.

Under the STEP Act, an officer could still issue a citation for 

a secondary offense (under one of the covered provisions) after 

stopping a driver for a primary offense. Even then, however, an 

officer could not cite a driver for a first violation of one of the 

covered provisions but rather would be required to give a verbal or 

written warning. STEP Act (proposed § 35-27(d)).

The second major topic of the STEP Act is searches during 

traffic stops—specifically, officers’ ability to request consent to 

search. Under the bill, an officer conducting a traffic stop could 

“only ask for permission to conduct a consent search of a person or 

vehicle if reasonable suspicion or probable cause for a criminal 

offense arises during the stop.”10 STEP Act (proposed § 35-27(e)). 

(§ 22-204(f)); driving a vehicle with inadequate stop lamps or turn signal 

lamps (§§ 22-206 and 22-219(a)); driving a vehicle that does not have 

lamps of the required colors (§ 22-209); driving a vehicle that does not 

have required rear reflectors (§ 22-210(c)); driving a vehicle with lamps 

that project “glaring or dazzling light” (§ 22-219(g)); using high beams 

when approaching another vehicle (§ 22-223); driving a vehicle with 

window obstructions (§ 22-404(a)); and driving a vehicle without safety 

glass or with window tints that are too dark (§ 22-406). The bill clarifies 

that notwithstanding the bill’s designation of various headlight-related 

offenses as secondary, an officer would still be able to stop a vehicle that 

does not have at least one front and rear light illuminated. STEP Act 

(proposed § 35-27(c)(2)(O)).

9

In 2021, violations of Title 13 (registration and license plates) 

accounted for 9.08% of all traffic stops by the MCPD; violations of Title 

16 (driver’s licenses) for 1.72%; and equipment violations under Title 22 

for 10.19% (although the data lump all equipment violations together, so 

there is no data on the number of traffic stops for the specific Title 22 

provisions covered by the STEP Act). See Data Dashboard (enter 

“Montgomery County Police Department” for “Agency” and “2021” for 

“Year”). There was no data on traffic stops under Title 17.

10 The STEP Act would also provide that an officer may not extend a 

traffic stop beyond its original purpose unless there is reasonable 

suspicion of another crime. STEP Act (proposed § 35-27(e)(1)). Other 

than eliminating consent as a basis for extending a stop, this is consistent 

with what the Fourth Amendment and Article 26 already require. See 

Ferris, 355 Md. at 372.
Gen. 81] 91

The STEP Act would thus eliminate “investigatory” traffic stops in 

which an officer requests consent to search for evidence of crimes 

beyond the motor vehicle offense that authorized the stop, without 

particularized suspicion of the driver or vehicle at issue. See OLO 

Report at 77. This rule would apply to all MCPD traffic stops, not 

just traffic stops where a secondary offense is involved. See STEP 

Act (proposed § 35-27(e)).

The STEP Act limits its coverage to the MCPD. It would not 

affect traffic stops by the State Police, municipal police, and other 

law enforcement agencies. STEP Act (proposed § 35-26(a)) 

(defining “police officer” as “a sworn officer employed by the 

County”). An officer conducting a traffic stop or search in 

violation of the STEP Act would be subject to discipline. Id.

(proposed § 35-27(f)). 

II

Analysis

You have asked whether the Maryland Vehicle Law would 

preempt the proposed STEP Act. Preemption occurs when State 

law precludes a local government from enacting a measure that 

would otherwise be within the local government’s power. 

Preemption may result from the express terms of a State statute, 

may be implicit in the comprehensiveness of a State statute’s 

coverage, or may occur when a local law directly conflicts with 

State law. See, e.g., 101 Opinions of the Attorney General 35, 55 

(2016). As we will explain, the Maryland Vehicle Law expressly 

preempts local governments from making law on any subject the 

Vehicle Law covers. And the Vehicle Law covers the subject of 

primary versus secondary offenses: it establishes a default rule of 

primary enforcement by empowering officers to issue a citation for 

any Vehicle Law offense, while mandating secondary enforcement 

for some specific offenses. Because the General Assembly has 

addressed the issue, local legislation cannot make different 

determinations on which traffic offenses should be primary and 

which secondary. But because the Vehicle Law says nothing about 

searches during traffic stops, it would not preempt the STEP Act’s 

limitations on consent searches. Nor would those limitations on 

searches conflict with any provision of the Vehicle Law.

A. General Principles of Preemption

Montgomery County has adopted the charter home rule form 

of government. See generally Md. Const., Art. XI-A. This status 

grants the county broad authority to enact local laws. See, e.g., 
92 [108 Op. Att’y

Montgomery Citizens League v. Greenhalgh, 253 Md. 151, 160-62 

(1969). But a charter county’s power has limits. Even a local law 

that is otherwise within the county’s power must yield if State law 

preempts it. See, e.g., Edwards Sys. Tech. v. Corbin, 379 Md. 278, 

296-97 (2004).

State law can preempt local law in one of three ways. E.g., 

Worton Creek Marina, LLC v. Claggett, 381 Md. 499, 512 (2004). 

First, express preemption occurs when a State statute explicitly 

precludes local governments from making law in a certain area. 98 

Opinions of the Attorney General 60, 88 (2013). We interpret 

express preemption provisions under the normal rules of statutory 

construction. See, e.g., 75 Opinions of the Attorney General 308, 

311-12 (1990). Under those rules, our primary objective is to 

determine and effectuate the intent of the General Assembly, 

beginning with the ordinary meaning of the language used, 

considered in context, and considering other sources of meaning, 

such as legislative history and the statute’s general purpose. E.g., 

107 Opinions of the Attorney General 196, 203 (2022).

The second form of preemption is implied preemption. “State 

law can preempt local ordinances by implication when ‘the 

ordinance deals with an area in which the General Assembly has 

acted with such force that an intent to occupy the entire field must 

be implied.’” Board of County Comm’rs v. Perennial Solar, LLC, 

464 Md. 610, 619 (2019) (quoting Howard County v. Potomac 

Elec. Power Co., 319 Md. 511, 522 (1990)). But a statute with an 

express preemption provision is unlikely to implicitly preempt, in 

this way, more than it expressly preempts. See Browning-Ferris, 

Inc. v. Anne Arundel County, 292 Md. 136, 153 (1981); see also

107 Opinions of the Attorney General 74, 83-84 (2022) (discussing 

this point in the context of federal-state preemption).

Third, conflict preemption occurs when a local law directly 

conflicts with State law. Maryland courts have recognized two 

sub-types of conflict preemption. First, a “verbal” conflict, also 

known as “prohibit-permit” conflict, exists when the local law 

would authorize something State law prohibits or would prohibit 

something State law expressly authorizes. 98 Opinions of the 

Attorney General at 91; Worton Creek, 381 Md. at 513. Second, a 

“functional” conflict exists when the impact of the local law 
Gen. 81] 93

interferes with the State law’s function. 96 Opinions of the 

Attorney General 139, 144 (2011).11

B. The STEP Act’s Secondary-Offense Provisions

We first consider whether the Vehicle Law would preempt the 

STEP Act’s secondary-offense provisions. Under the Vehicle 

Law, a local government may not “make or enforce any local law, 

ordinance, or regulation on any subject covered by the Maryland 

Vehicle Law” except as expressly authorized. TR § 25-101.1(b)(3); 

accord TR § 25-101.1(c)(1). Our Office has described this 

provision as representing “some of the most far-reaching 

preemption in State law.” Letter from Kathryn M. Rowe, Assistant 

Attorney General, to Del. Brooke E. Lierman, at 1 (Oct. 10, 2018); 

see also 93 Opinions of the Attorney General 126, 134 (2008) 

(characterizing the Vehicle Law’s express preemption provision as 

especially “open-ended”). 

To determine whether the Vehicle Law preempts a local law 

under § 25-101.1, we must answer three questions: First, is the 

local measure at issue a “local law, ordinance, or regulation”? 

Second, does it address a “subject covered by the Maryland Vehicle 

Law”? Third, does any other State law “expressly authorize[]” the 

measure? If the measure is a “local law, ordinance, or regulation” 

on a “subject covered by the Maryland Vehicle Law,” and no other 

State law expressly authorizes it, the local enactment is preempted.

Answering the first question is straightforward: if enacted by 

the County Council, the STEP Act would clearly be a “local law” 

or “ordinance” within the meaning of TR § 25-101.1. The other 

two questions require more detailed analysis.

1. Subject Covered by the Maryland Vehicle Law

As to the second question, our opinion is that the STEP Act’s 

secondary-offense provisions address a “subject covered by the 

Maryland Vehicle Law”: the determination of which motor vehicle 

offenses are primary and which are secondary.

11 Federal law also recognizes “obstacle” or “frustration of purpose” 

preemption, when a state law “stands as an obstacle to the 

accomplishment and execution of the full purposes and objectives of 

Congress.” E.g., Arizona v. United States, 567 U.S. 387, 399 (2012) 

(quoting Hines v. Davidowitz, 312 U.S. 52, 67 (1941)). But Maryland 

courts have so far declined to import this doctrine into the State versus 

local law context. E.g., County Council of Prince George’s County v. 

Chaney Enters. Ltd. P’ship, 454 Md. 514, 541 n.19 (2017).
94 [108 Op. Att’y

Several of our prior opinions have considered whether 

particular local laws addressed subjects covered by the Vehicle 

Law. For example, in one opinion, we concluded that when State 

law required minors (and only minors) to wear motorcycle helmets, 

Baltimore City could not impose the same requirement on adults, 

because the Vehicle Law covered the subject of “safety equipment 

required of motorcycle operators,” 65 Opinions of the Attorney 

General 483, 484, 486-87 & n.7 (1980). Later, our Office 

concluded in a different opinion that a city ordinance could address 

charitable and employment solicitations from sidewalks, from 

vehicles, and in parking lots, where the Vehicle Law addressed 

only solicitation by pedestrians standing in the roadway. 93 

Opinions of the Attorney General 31, 33, 36-37 (2008). Another 

opinion concluded that a city could regulate parking on private 

property with the property owner’s consent because the Vehicle 

Law only regulates parking on private property without the 

property owner’s consent. 73 Opinions of the Attorney General 

252, 254-55 (1988).12

As these opinions illustrate, the level of generality at which 

the Vehicle Law’s preempted “subjects” should be defined is not 

always clear. Our 2008 opinion on roadway solicitation, for 

example, would presumably have reached the opposite result if we 

had defined the covered “subject” as solicitation in a roadway 

rather than solicitation by pedestrians in a roadway; this would 

have preempted the local ban on solicitation from vehicles. 

Similarly, our 1980 opinion on motorcycle helmets would likely 

have reached the opposite result if it had defined the covered 

subject as “motorcycle safety equipment required of minors,” 

thereby saving Baltimore City’s adult helmet requirement from 

preemption. 

Even though it may not always be clear how broadly (or 

narrowly) to define the “subjects” covered by the Vehicle Law, it 

is clear that when a local law addresses a matter that specific 

provisions of the Vehicle Law also directly address, the local law 

12 In Mayor & City Council of Baltimore v. Hart, 395 Md. 394 (2006), 

Maryland’s highest court held that the Vehicle Law did not preempt a 

Baltimore City Police Department general order setting rules for 

emergency vehicles that were stricter than State law, id. at 406. 

However, for reasons that are not clear from the opinion or briefing, the 

question of express preemption under TR § 25-101.1 was not presented 

in Hart. See id. at 406-10 (discussing conflict preemption only). It is 

also possibly relevant that Hart involved a departmental order rather than 

a “local law, ordinance, or regulation.” See id. at 404; see also infra Part 

II.B.3.
Gen. 81] 95

will be preempted. The level of generality problem has arisen only 

when a local law has addressed something that the Vehicle Law 

does not directly address—such as motorcycle helmets for adults 

or solicitation from cars—but that was arguably related to, and thus 

possibly part of the same broader “subject” as, a matter the Vehicle 

Law did address. But there is no question that the Vehicle Law 

would preempt a local law on a subject the Vehicle Law directly 

speaks to. See, e.g., 58 Opinions of the Attorney General 462, 464 

(1973) (concluding that a local ordinance, intended to prevent 

debris from falling off trucks, was preempted because the Vehicle 

Law also had a provision requiring the securing of truck loads). 

Here, the Vehicle Law directly addresses which offenses are 

primary and which are secondary through a rule that applies to all 

offenses under the Vehicle Law. More specifically, § 26-201 of 

the Transportation Article establishes that an officer may issue a 

citation for a violation of any Vehicle Law provision, if the officer

has probable cause to believe the person has committed or is 

committing the violation. TR § 26-201(a). The General Assembly 

added this provision in 1977 to make explicit a power that had 

previously been implicit. 1977 Md. Laws, ch. 186; Commission to 

Revise the Annotated Code, Report on S.B. 501, 1977 Leg., Reg. 

Sess., at 4 (Feb. 22, 1977). Although the statute refers only to 

citations and not explicitly to traffic stops, the authority to issue a 

citation for a motor vehicle offense implies the authority to make a 

traffic stop, because the statute requires that the citation be issued 

to and acknowledged by the driver. See TR §§ 26-201(b), 26-203. 

And more importantly, by authorizing an officer to issue a citation 

for any motor vehicle offense without regard to whether another 

offense has been committed, TR § 26-201 provides for primary 

enforcement of all motor vehicle offenses. If an officer can cite a 

driver for a given offense, without more, that offense is necessarily 

primary. The Vehicle Law thus addresses the subject of primary 

versus secondary enforcement of the motor vehicle laws by 

establishing a general rule of primary enforcement.

As exceptions to that general rule, the General Assembly has 

expressly designated some specific motor vehicle violations as 

secondary. See, e.g., TR § 21-1104(c)(3) (driving with an object 

hanging from the rearview mirror); TR § 13-411(c)(2) (driving 

with a frame or border partially obscuring the license plate); see 

also supra Part I.C (listing other examples). Typically, an officer 

may enforce one of these provisions only after stopping a driver for 

a suspected violation of a different provision. E.g., TR 

§ 21-1104(c)(3)(ii). So, for example, an officer could not stop or 

cite a driver who was driving with an object hanging from the 
96 [108 Op. Att’y

rearview mirror but otherwise obeying the law. If the driver then 

ran a red light, however, an officer could stop the driver and cite 

them for both offenses. The General Assembly’s express 

categorization of certain offenses as secondary confirms that the

Vehicle Law covers the subject of which motor vehicle offenses 

are primary and which are secondary. Reading the Vehicle Law as 

a whole, as we are required to do, e.g., 105 Opinions of the Attorney 

General 3, 16 (2020), these secondary-offense provisions are best 

read as exceptions to the general rule of primary enforcement 

established by TR § 26-201.

Indeed, under standard principles of statutory interpretation, 

the General Assembly’s establishment of these specific exceptions 

indicates an intent that the general rule should apply in all cases not 

expressly excepted. See, e.g., 85 Opinions of the Attorney General

80, 83 (2000) (noting that “exceptions are strictly construed”); 

Leppo v. State Highway Admin., 330 Md. 416, 423 (1993) (“When 

the legislature has expressly enumerated certain exceptions to a 

principle, courts normally should be reluctant thereafter to create 

additional exceptions.” (quoting Ferrero Constr. Co. v. Dennis 

Rourke Corp., 311 Md. 560, 575 (1988)); Department of Motor 

Vehicles v. Greyhound Corp., 247 Md. 662, 668 (1967) (“By 

making these two items the sole exceptions, the statute is as plain 

as if it had listed all of the [items] not included in the exceptions.”). 

And, consistent with that understanding, where the General 

Assembly has chosen to make particular offenses secondary, the 

legislative history of those enactments expressly recognized that 

“[e]xcept as otherwise specified, violations of the Maryland 

Vehicle Law are subject to primary enforcement.” Fiscal & Policy 

Note, H.B. 1335, 2017 Leg., Reg. Sess., at 1; accord Fiscal & 

Policy Note, S.B. 859, 2020 Leg., Reg. Sess., at 2 (same). Thus, 

read as a whole, the Vehicle Law addresses the subject of primary 

versus secondary enforcement: it establishes a rule that, unless the 

Vehicle Law has expressly designated a motor vehicle offense as 

secondary, the offense is subject to primary enforcement.

Especially illustrative are the instances where the General 

Assembly has redesignated a formerly primary offense as 

secondary. 2020 Md. Laws, ch. 107 (frame or border partly 

obscuring license plate); 2017 Md. Laws, ch. 756 (object hanging 

from rearview mirror). In each of these cases, a major purpose of 

the change was to reduce racially disparate traffic enforcement. 

Hearing on H.B. 200 Before the House Env’t & Transp. Comm., 

2020 Leg., Reg. Sess., at 1:08:10-1:09:50 (Feb. 13, 2020) (“H.B. 

200 Hearing”) (statement of Del. Fisher); Hearing on H.B. 1335 

Before the House Env’t & Transp. Comm., 2017 Leg., Reg. Sess., 
Gen. 81] 97

at 2:29:40-2:30:30 (Mar. 9, 2017) (“H.B. 1335 Hearing”) 

(statement of Del. Wilkins). But, in each case, the Legislature 

chose to establish secondary enforcement for only some of the 

conduct the provision covered and keep primary enforcement for 

the rest. As to license plates, for instance, the Legislature provided 

secondary offense status only for objects obscuring the frame or 

border of a license plate and left primary enforcement in place for 

material covering the actual plate number. See 2020 Md. Laws, ch. 

107. Similarly, as to windshield obstruction, the General Assembly 

downgraded driving with material hanging from the rearview 

mirror to a secondary offense, while retaining primary enforcement 

for other instances where an object obstructs a driver’s view 

through the windshield. See 2017 Md. Laws, ch. 756. 

In other instances, legislative proposals to make particular 

offenses secondary have failed. For example, when the General 

Assembly in 2009 passed legislation to prohibit texting while 

driving, see 2009 Md. Laws, ch. 194 (enacting TR § 21-1124.1), 

the Senate rejected a proposed floor amendment that would have 

made texting while driving a secondary offense, see Amend. No. 

463122/1, S.B. 98, 2009 Leg., Reg. Sess., with the understanding 

that if the amendment were rejected the offense would be primary, 

see Senate Floor Proceedings No. 43, 2009 Leg., Reg. Sess., at 

23:00-23:48 (Mar. 13, 2009) (statement of Sen. Zirkin). This 

further supports the view that the Vehicle Law establishes a general 

rule of primary enforcement for motor vehicle offenses and that 

preservation of that general rule, for offenses not explicitly 

declared secondary, is intentional on the part of the Legislature. 

Balancing the benefits and costs of secondary enforcement for a 

given offense is a policy judgment, and the Vehicle Law’s express 

preemption provision reserves that policy judgment to the General 

Assembly.

Perhaps if the Vehicle Law only designated certain offenses 

as secondary, and was otherwise silent as to how the traffic laws 

are to be enforced, the case for preemption would be weaker. But 

the combination of the general rule allowing police officers to cite 

drivers for any Vehicle Law offense—which indicates that such 

offenses are generally subject to primary enforcement—and the 

specific exemptions for situations where the Legislature has 

determined secondary enforcement to be appropriate, causes us to 

conclude that the Maryland Vehicle Law covers the subject of 

primary versus secondary enforcement of motor vehicle offenses. 

Thus, a local law may not address that subject absent express 

authorization by the General Assembly.
98 [108 Op. Att’y

2. Express Authorization by Other State Law

The third question under the Vehicle Law’s express 

preemption provision is whether, even if the STEP Act’s 

secondary-offense provisions involve a subject covered by the 

Vehicle Law, there is nonetheless a separate express authorization 

for local governments to legislate on that subject. The Vehicle Law 

does, alongside its broad preemption provision, expressly reserve 

certain powers to localities. TR § 25-102(a). We thus need to 

consider whether any of those powers would authorize the STEP 

Act’s secondary-offense provisions.

The list of enumerated local powers in § 25-102(a) dates back 

to 1943. Before that year, the Vehicle Law had contained—

alongside the general preemption provision enacted in 1927—a 

provision authorizing local governments to promulgate 

“reasonable traffic regulations.” Md. Ann. Code, Art. 56, § 145 

(1939). As part of its 1943 revision to the Vehicle Law, which 

sought to “promot[e] greater uniformity,” 1942 Report at 8, the 

General Assembly repealed that broad power. See 1943 Md. Laws, 

ch. 1007. In its place, the Legislature enacted a list of six specific 

local powers (copied almost verbatim from the 1938 Uniform 

Vehicle Code) and provided that the Vehicle Law “shall not be 

deemed to prevent local authorities” from exercising those powers. 

Compare 1943 Md. Laws, ch. 1007 (enacting Art. 66 1⁄2, § 135), 

with Uniform Vehicle Code, Uniform Act Regulating Traffic on 

Highways § 28, at 5 (1938 rev.).13

One of the reserved powers is “regulating or prohibiting the 

stopping, standing, or parking of vehicles.” TR § 25-102(a)(1) 

(emphasis added). On its face, this provision might appear to cover 

traffic “stops” by police. But “stop” is a defined term under the 

13 The six local powers enumerated in 1943 were: “(1) Regulating the 

standing or parking of vehicles; (2) Regulating traffic by means of police 

officers or traffic control devices; (3) Regulating or prohibiting 

processions or assemblages on the highways; (4) Designating particular 

highways as one way highways and requiring that all vehicles thereon be 

moved in one specific direction; (5) Regulating the speed and weight of 

vehicles in public parks; (6) Designating any intersection as a stop 

intersection requiring all vehicles to stop at one or more entrances to such 

intersections.” 1943 Md. Laws, ch. 1007 (enacting Art. 66 1⁄2, § 135). 

These provisions are now codified, with minimal changes, at TR 

§ 25-102(a)(1)-(6). The General Assembly has since added further items 

to the list, but the new items are not substantially different in character 

from the original six; all essentially relate to the control of traffic on 

roads under the local government’s jurisdiction. See TR § 25-102(a).
Gen. 81] 99

Vehicle Law, TR § 11-162, and when used in a “prohibitory 

sense”—the sense in which § 25-102(a)(1) uses it—the term “stop” 

excludes instances where a vehicle stops “in compliance with the 

directions of a police officer,” TR § 11-162(2). Also, the context 

in which the word “stopping” is used in § 25-102(a)(1)—together 

with “standing” and “parking”—implies that the provision is 

concerned with where and when a driver may stop or park their 

vehicle safely, not with officer-initiated traffic stops. See Shivers

v. State, 256 Md. App. 639, 664 (2023) (noting that in statutory 

interpretation “the meaning of a word is or may be known from the 

accompanying words” (quoting Emmert v. Hearn, 309 Md. 19, 25 

(1987)). 

The provision’s history accords with that understanding. 

Section 25-102(a)(1) originally omitted the word “stopping,” even 

though that word had appeared in the Uniform Vehicle Code 

provision on which the Maryland provision was modeled. 

Compare 1970 Md. Laws, ch. 534 (enacting Art. 66 1⁄2, 

§ 15-102(a)(1)), with Uniform Vehicle Code § 15-102(a)(1), at 230 

(1968 rev.). The word “stopping” was added seven years later 

during the code revision process to correct this “oversight.” 1977 

Md. Laws, ch. 14 (Revisor’s Note to TR § 25-102). Because the 

code revision process generally is not intended to make substantive 

changes to the law, this history implies that the General Assembly 

did not see the addition of “stopping” alongside “standing” and 

“parking” as changing the scope of the power. See, e.g., 

Comptroller v. Blanton, 390 Md. 528, 538-39 (2006).

Local governments also have the power of “[r]egulating 

traffic by means of police officers or traffic control devices.” TR 

§ 25-102(a)(2). This provision, in our view, recognizes that local 

governments may employ police officers to direct traffic and 

control the movement of vehicles on the roadway, as necessary to 

ensure safe and efficient traffic flow. But we do not think it 

empowers local authorities to revise the General Assembly’s 

determination on whether a traffic offense is primary or secondary.

To begin, we note that the provision speaks of “regulating 

traffic.” “Traffic” means the physical movement of vehicles on a 

highway. See TR § 11-166. So “regulating traffic” most naturally 

means directing traffic, i.e., controlling the movement of vehicles 

and traffic flow. The provision recognizes that local governments 

may regulate traffic in two ways—“by means of” either police 

officers or traffic control devices, TR § 25-102(a)(2), with the latter 

referring to traffic lights, stop signs, and the like, TR § 11-167. 

This, again, suggests that § 25-102(a)(2) contemplates police 
100 [108 Op. Att’y

officers acting in a role similar to a traffic light or stop sign—

directing traffic in the ordinary course of its movement. The other 

provisions enacted alongside § 25-102(a)(2) in 1943 similarly 

relate to the control of physical traffic movement, akin to the 

placement of traffic signals, such as designation of a street as a oneway street or of an intersection as a four-way stop. See 1943 Md. 

Laws, ch. 1007. As Maryland courts often say, “the meaning of the 

plainest language is controlled by the context in which it appears.” 

E.g., Elsberry v. Stanley Martin Cos., 482 Md. 159, 181 (2022) 

(quoting Building Materials Corp. of Am. v. Board of Educ., 428 

Md. 572, 585 (2012)). Here, the context indicates that 

§ 25-102(a)(2)’s reference to “regulating traffic by means of police 

officers” addresses what it seems, at first glance, to address—local 

authority to have police officers control and direct traffic 

movement. 

But even if § 25-102(a)(2)’s coverage is broader than just that, 

we cannot identify a reading of that provision that is both broad 

enough to encompass the authority to redesignate primary offenses 

as secondary and also consistent with the provision’s text, context, 

and history. That is, we doubt that the General Assembly intended 

to enable localities to alter the legislative judgment that “[e]xcept 

as otherwise specified, violations of the Maryland Vehicle Law are 

subject to primary enforcement.” E.g., Fiscal & Policy Note, H.B. 

1335, 2017 Leg., Reg. Sess. at 1. A police officer’s statutory 

authorization to issue a citation for any Maryland Vehicle Law 

offense, except those explicitly designated as secondary offenses 

by the General Assembly, reflects that general rule of primary 

enforcement. See TR § 26-201. Again, we interpret statutory 

schemes, as far as possible, to form a harmonious whole. E.g., 

Lockshin v. Semsker, 412 Md. 257, 276 (2010). For example, in a 

prior opinion, we concluded that even though local governments 

have the express authority to regulate parking, they cannot adopt 

procedures for handling parking violations that differ from the 

procedure in State law. 78 Opinions of the Attorney General 263, 

264-65 (1993). Here, too, we think the exercise of any power under 

§ 25-102(a)(2) must be consistent with the overall statutory scheme 

of the Vehicle Law.14

14 Our reading of § 25-102(a)(2) is also consistent with the principle 

that a statute should be construed so that none of its language “is 

rendered surplusage, superfluous, meaningless, or nugatory.” E.g., Rowe 

v. Maryland Comm’n on Civil Rights, 483 Md. 329, 342 (2023) (quoting 

Mayor & Town Council of Oakland v. Mayor & Town Council of 

Mountain Lake Park, 392 Md. 301, 316 (2006)). In particular, 

§ 25-102(a)(1) and § 25-102(a)(2) address distinct topics under our 
Gen. 81] 101

Authority from other jurisdictions supports our view as well. 

As noted above, § 25-102(a)(2)’s language comes from the 

Uniform Vehicle Code. Other states have interpreted their parallel 

provisions consistent with our view that § 25-102(a)(2) authorizes 

localities to use police to regulate the movement of traffic in 

accordance with law but not to alter the rules of traffic enforcement 

themselves. For example, the Minnesota Supreme Court held that 

the effect of a provision with near-identical language “is only to 

authorize a city to direct the movement of vehicles on the 

roadway.” State v. Kuhlman, 729 N.W.2d 577, 582 (Minn. 2007); 

see also id. at 582-84 (holding that state law preempted city attempt 

to authorize red light cameras). Similarly, the Florida Supreme 

Court in Masone v. City of Aventura, 147 So.3d 492, 497 (Fla. 

2014), concluded that the purpose of its own parallel statutory 

language was to allow local governments to control the movement 

of traffic but not to alter the statutory rules of traffic enforcement. 

In contrast, we know of no jurisdiction that has interpreted this 

provision to authorize a locality to redesignate a primary traffic 

violation as secondary.

3. The Role of Enforcement Discretion

One might argue that our conclusion clashes with the 

enforcement discretion normally vested in police departments and, 

interpretation: § 25-102(a)(1) covers rules for where drivers can stop or 

park their vehicles, and § 25-102(a)(2) deals with the control of active 

traffic flow by official authority, namely officers or traffic signals. One 

might also argue that, unless § 25-102(a)(2) authorizes some subject 

matter that would otherwise be preempted, § 25-102(a)(2) serves no 

purpose. But the provisions of § 25-102(a) may have been intended 

primarily for the avoidance of doubt, that is, to eliminate any suggestion 

that the listed subjects are preempted. Indeed, § 25-102(a) seems to 

cover at least some matters that would not have been preempted even 

absent § 25-102(a)’s enactment. For example, § 25-102(a)(12) 

authorizes localities to “[a]dopt[] any other traffic regulations as 

specifically authorized in the Maryland Vehicle Law,” which (because it 

merely refers to authorization granted elsewhere) would necessarily be 

surplusage under a strict application of the canon. Finally, it is an equally 

well-established rule of statutory interpretation that interpreters should 

neither “add nor delete language so as to reflect an intent not evidenced 

in the plain and unambiguous language of the statute,” nor should they 

“construe a statute with forced or subtle interpretations that limit or 

extend its application.” E.g., Rowe, 483 Md. at 342 (quoting Lockshin, 

412 Md. at 275). As we have explained, § 25-102(a)(2) speaks only to 

“regulating traffic,” and we think it would require a “forced” 

interpretation to stretch that language to encompass the designation of 

traffic violations as primary or secondary.
102 [108 Op. Att’y

thus, in the local governments that employ those police 

departments. No police department enforces all of the traffic laws 

all of the time—as anybody who has driven on a highway knows 

from observing that the speed of traffic is usually five or ten miles 

per hour above the speed limit. Generally, the decision whether to 

stop or detain a driver for a motor vehicle offense is a matter of the 

individual officer’s discretion, even when the officer has observed 

a probable violation. See Ashburn v. Anne Arundel County, 306 

Md. 617, 624 (1986). Indeed, current departmental policy of the 

MCPD explicitly grants officers “discretion in the enforcement of 

traffic laws” and states that “[a] written warning is appropriate . . . 

where a minor equipment defect is apparent.” MCPD, FC No. 

1000, Traffic Management System, § VIII(A)-(B) (July 1, 2022).

It also seems clear that a local government generally has 

authority to set internal operating rules for its own agencies, 

including the local police department. “The authority to establish 

a police force would be futile if it did not carry with it, at least by 

implication, the authority to enact reasonable rules for the effective 

administration of the force . . . .” 16A McQuillin: The Law of 

Municipal Corporations § 45:14 (3d ed., June 2023 update). The 

question arises, then, why a local legislative body cannot adopt 

something akin to the STEP Act as a way of setting rules for the 

exercise of enforcement discretion for its own local police 

department.

It may well be that, as a general matter, the County Council 

could by ordinance set enforcement priorities for the county police 

department. But whatever legislative authority the County Council 

might possess is overridden in this specific area by the General 

Assembly’s decision to preempt “local law[s]” and “ordinance[s]” 

addressing “subject[s]” covered by the Vehicle Law. TR 

§ 25-101.1(b)(3). In this particular area of motor vehicle law—that 

is, whether an offense is primary or secondary—the Legislature has 

decided as a policy matter that the need for statewide uniformity 

outweighs local governments’ legislative autonomy. See 65 

Opinions of the Attorney General at 486. Simply put, then, the 

County Council may not legislate on a subject the General 

Assembly has fenced off, even when it would have full power to 

act but for the preemption statute. See 101 Opinions of the Attorney 

General at 55-57 (concluding that preemption limits a county 

governing body’s power to place conditions on appropriations in 

the context of public library funding).

We also express no opinion about whether the county police 

department could adopt, on its own authority, an internal policy 
Gen. 81] 103

resembling the STEP Act. The MCPD currently has internal 

policies, issued by the Chief of Police, on a variety of subjects. See 

generally MCPD, Department Policies, https://www.montgomery

countymd.gov/pol/resource/policies.html (last visited Sept. 13, 

2023). Express preemption under TR § 25-101.1 applies only to a 

“local law, ordinance, or regulation,” and there is at least a question 

as to whether an executive branch agency’s internal policy, which 

is subject to change at any time and merely communicates how the 

agency plans to exercise its discretion, would qualify as a local law, 

ordinance, or regulation, especially when the policy might not need 

to be promulgated as a formal regulation under the applicable 

administrative procedure statute. Cf. Montgomery County Code 

§ 35-3(c) (indicating that county administrative procedure law 

governs the adoption of police “regulations” but not “orders”). In 

any event, we need not decide whether a police department could 

adopt such a policy to answer the question that you have asked. We 

conclude only that a local legislative body may not designate a 

traffic offense as secondary when State law has not done so.15

C. The STEP Act’s Consent-Search Provision

The STEP Act would also prohibit an MCPD officer from 

requesting consent to search, during a traffic stop, unless 

reasonable suspicion or probable cause “arises during the stop.” 

STEP Act (proposed § 35-27(e)(2)). For the reasons explained 

below, the Vehicle Law’s express preemption provision would not 

cover this aspect of the STEP Act, because the Vehicle Law does 

not address the conditions under which an officer may search a 

vehicle, or its occupants, during a traffic stop. Nor does the 

Vehicle Law establish implied field preemption beyond the scope 

of its express preemption clause. And a restriction on searches 

during stops would not conflict with any provision of the Vehicle 

Law. Accordingly, the Vehicle Law would not preempt the STEP 

Act’s consent-search provision.16

15 Because we conclude that the STEP Act’s secondary-offense 

provisions would be expressly preempted, we need not consider whether 

they would be subject to implied or conflict preemption.

16 Your opinion request asked only whether the Vehicle Law would 

preempt the STEP Act. We thus limit our preemption analysis to the 

Vehicle Law. We also note that the STEP Act’s provision precluding 

collective bargaining on the matters covered by the STEP Act (proposed 

§ 33-80) would not be preempted by the Vehicle Law for similar reasons 

to those discussed here: the Vehicle Law does not address collective 

bargaining or require collective bargaining on any particular topic, so no 

form of preemption would apply. 
104 [108 Op. Att’y

1. Express Preemption

As we have explained, express preemption under the Vehicle 

Law applies only when a local law, ordinance, or regulation 

addresses a “subject covered by the Maryland Vehicle Law.” TR 

§ 25-101.1(b)(3). Although the Vehicle Law’s enforcement 

provisions cover procedures for citation, arrest, and prosecution for 

motor vehicle offenses, see generally TR §§ 26-201 to 26-412, 

nothing in the Vehicle Law prescribes the circumstances under 

which an officer may, or may not, conduct a search during a traffic 

stop or otherwise. In short, the Vehicle Law is not the source of an 

officer’s authority to search.17 Thus, the Vehicle Law does not 

expressly preempt a local law limiting a local police department’s 

authority to conduct searches, because searches are “altogether 

beyond the purview of the Vehicle Law.” See 71 Opinions of the 

Attorney General 400, 404 (1986) (concluding that the Vehicle 

Law does not address speed bumps).

2. Implied Preemption

Implied preemption occurs when the “General Assembly has 

acted with such force that an intent to occupy the entire field must 

be implied.” Perennial Solar, 464 Md. at 619. But we do not think 

the Vehicle Law implicitly preempts a field broader than its express 

preemption provision. In other words, if a local law is not subject 

to the Vehicle Law’s express preemption provision, it is likely not 

subject to implied preemption either. Normally, when the General 

Assembly specifies the items to which a law will apply, we will 

infer that the exclusion of other items was intentional. See 98 

Opinions of the Attorney General 3, 12 (2013) (discussing the 

canon of construction expressio unius est exclusio alterius, or “the 

expression of one thing is the exclusion of another”). That 

principle applies to preemption as well. When the General 

Assembly has drafted an express preemption provision, it is usually 

a reasonable inference that the Legislature considered the breadth 

of the field it wanted to preempt and that the express preemption 

provision corresponds to that intent. See Browning-Ferris, 292 

Md. at 153 (holding that the enactment of a narrower express 

preemption provision overrode what had been “a very strong case” 

for broader implied preemption). Although we do not foreclose the 

possibility that legislative intent could indicate implied preemption 

extending beyond the bounds of express preemption within the 

17 TR § 25-113 requires law enforcement agencies to gather certain 

data on searches during traffic stops and to adopt a policy against racebased traffic stops that does not affect an officer’s otherwise existing 

authority to search, but it does not, itself, grant authority to search.
Gen. 81] 105

context of a particular statutory scheme, we see no evidence of such 

an intent here. The Vehicle Law therefore would not implicitly 

preempt the STEP Act’s consent-search provision.

3. Conflict Preemption

Conflict preemption is the third and final form of preemption 

Maryland law recognizes. The first type of conflict preemption, 

and the one Maryland courts most frequently consider, is “verbal” 

or “prohibit-permit” conflict. Under this type of conflict 

preemption, local law may not permit what State law prohibits, nor 

may local law prohibit what State law affirmatively permits. See

Mayor & City Council of Baltimore v. Sitnick, 254 Md. 303, 317 

(1969). There is no preemption if State law permits something 

simply by not addressing it; rather, State law must affirmatively 

authorize an activity before a local law prohibiting that activity will 

be preempted. Coalition for Open Doors v. Annapolis Lodge No. 

622, Benevolent & Protective Order of Elks, 333 Md. 359, 380 

(1994). As we have discussed, the Vehicle Law is silent on 

searches; it neither prohibits them, nor expressly permits 

them. Accordingly, there would be no verbal conflict between the 

Vehicle Law and a local prohibition on consent searches.

The second type of conflict preemption is “functional 

conflict.” The courts have not been as clear about what a functional 

conflict involves. But, “[i]n general, some element of 

irreconcilability or legal inconsistency is required, such that both 

the State and local laws cannot be applied together.” 93 Opinions 

of the Attorney General at 135. We see no inconsistency or 

irreconcilability between the Vehicle Law and the STEP Act’s 

consent-search provisions.

The consent-search provision would not create a problem 

analogous to any of the situations where courts have found 

functional conflicts. See Coalition for Open Doors, 333 Md. at 380 

n.39 (citing functional conflict cases). First, the consent-search 

provision would not create a situation where there would be 

conflicting rules in the same area such that a police officer could 

not simultaneously comply with State and local law. See 

Montgomery County v. Board of Supervisors of Elections, 311 Md. 

512, 517 (1988) (finding functional conflict when State and local 

law provided irreconcilable methods of appointing the same 

officers). The provision also would not prohibit a local 

government from taking action that is required under State law. See 

East v. Gilchrist, 296 Md. 368, 373-74 (1983) (finding functional 

conflict where local charter prohibited county from spending 
106 [108 Op. Att’y

money that State law required it to spend). Nor would it create a 

“direct conflict with a State statute regulating the same matter,” 

Worton Creek, 381 Md. at 514 (discussing Montgomery County Bd. 

of Realtors v. Montgomery County, 287 Md. 101, 109-10 (1980), 

in which the Court held that a local tax conflicted with the State’s 

scheme for assessment of real property), because, again, the 

Vehicle Law does not regulate searches.

We have also suggested that a functional conflict may exist 

when a local law interferes with the functioning of a State law. See

98 Opinions of the Attorney General at 91. We would be cautious 

about finding a functional conflict on this basis alone, given that 

Maryland courts have repeatedly declined to adopt the similar 

federal doctrine of obstacle preemption, under which a law is 

preempted if it frustrates the purpose of a federal statute. E.g., 

Chaney, 454 Md. at 541 n.19. But even assuming State law can 

preempt local law in this way as a general matter, this is not such a 

case. 

The purpose of the Vehicle Law is to ensure the safe and 

efficient movement of traffic, and to prevent crashes and injuries 

on roadways. Supra Part I.B. By contrast, the functional effect of 

the consent-search provision of the STEP Act is to limit an officer’s 

authority to search an already-stopped vehicle. Because these 

provisions of the Act would only limit what an officer can do once 

the vehicle has already been stopped, their impact on traffic 

enforcement would be minimal—given that traffic violations are 

meant to be observable before the vehicle has been stopped. When 

an officer seeks consent to search a stopped vehicle, despite lacking 

any particularized suspicion of a crime, their purpose is usually not 

to enforce the traffic laws but to search for evidence of other 

crimes, like possession of contraband. See, e.g., LaFave, supra, at 

1891-92. Perhaps there might be some circumstances where 

evidence of a motor vehicle offense could only be revealed through 

a suspicionless consent search, but we think such cases will be 

rare. The STEP Act’s consent-search provision thus would not 

interfere with the Vehicle Law’s functioning to such a degree as to 

be preempted.

III

Conclusion

In our opinion, the Maryland Vehicle Law would preempt a 

local law, such as the STEP Act, that would designate a violation 

of the Vehicle Law as secondary when State law has not designated 

it as such. This is because the determination of which motor 
Gen. 81] 107

vehicle offenses are primary, and which are secondary, is a subject 

covered by the Vehicle Law. And neither the local power to 

regulate “stopping, standing or parking,” TR § 25-102(a)(1), nor 

the local power to “regulate traffic by means of police officers,” 

TR § 25-102(a)(2), authorizes a local government to redesignate a 

Vehicle Law offense from primary to secondary status. On the 

other hand, the Vehicle Law would not preempt a local law limiting 

a local police officer’s ability to request consent to search during 

traffic stops. Because the Vehicle Law does not address the 

conditions under which searches are permissible, such a local law 

would neither intrude on a subject covered by the Vehicle Law nor 

conflict with the Vehicle Law.

Anthony G. Brown

Attorney General of Maryland

Thomas S. Chapman

Assistant Attorney General

Patrick B. Hughes

Chief Counsel, Opinions and Advice