A county ordinance cannot supersede state law. Counties are subdivisions of the state, not independent sovereigns, so when a valid state statute and a county ordinance conflict, the state statute controls and the ordinance is unenforceable to the extent of the conflict. The U.S. Supreme Court settled the underlying principle more than a century ago, holding that a state may “modify or withdraw all such powers” from its local governments “at its pleasure.”1Justia Law. Hunter v. City of Pittsburgh – 207 U.S. 161 (1907) That is the ceiling. Below it, how much a county can actually do depends on the authority its state has delegated and whether the legislature has signaled that it means to be the only voice on a given subject.
Why the State Wins
Local governments have no independent constitutional standing. The U.S. Constitution allocates power between the federal government and the states and says nothing about counties or cities. Counties exist because the state created them, and they exercise only the powers the state allows. In Hunter v. City of Pittsburgh, the Court described local governments as “political subdivisions of the state, created as convenient agencies for exercising such of the governmental powers of the state as may be entrusted to them.”1Justia Law. Hunter v. City of Pittsburgh – 207 U.S. 161 (1907) The state can expand a county’s powers, shrink them, or eliminate them.
A state statute and a county ordinance therefore sit on different rungs. The legislature acts under its own constitutional authority. A county board acts under delegated authority. When the two collide, the delegation loses. Lawyers call the doctrine preemption, and it works between state and local law the same way it works between federal and state law: the higher authority controls.
How Much Latitude a County Starts With
Before you even get to a preemption fight, a county’s authority is shaped by whether it operates under Dillon’s Rule or Home Rule. These frameworks, set by each state’s constitution or statutes, produce very different starting points.
Dillon’s Rule
Named for Iowa judge John Forrest Dillon, who articulated the principle in 1868, Dillon’s Rule takes the restrictive view. A county can exercise only powers the state expressly grants, powers reasonably implied by that grant, and powers essential to the county’s basic functioning. When there is doubt, the answer is no, and courts resolve ambiguity against the local government. Somewhere between 30 and 40 states apply some version of Dillon’s Rule to at least some of their local governments.
Home Rule
Home Rule flips the presumption. A Home Rule county has broad authority to legislate on local matters unless the state has forbidden it, and does not need specific permission for each new ordinance. The limit is the same limit that applies everywhere: the ordinance still cannot conflict with state or federal law. About 10 states are considered pure Home Rule states, and most of the rest use a hybrid approach or extend Home Rule only to certain localities based on population or local referendum.
The distinction matters for how likely a county ordinance is to survive scrutiny, but it does not change the answer to the core question. Neither system lets a county override a state statute on the same subject.
The Three Ways a State Preempts Local Law
When a state does preempt, courts sort the situation into one of three categories. Which one applies changes the legal argument.
Express Preemption
The legislature says so, in the statute itself. The text might read that “no county or municipality may enact any ordinance regulating” a particular subject. There is no ambiguity. Firearms regulation is the leading example: roughly 45 states expressly preempt local governments from passing their own gun laws to some degree.
Field Preemption
Sometimes called implied preemption. The legislature has not written “locals keep out,” but it has regulated an area so completely that a court infers the state meant to occupy the entire field. Mortgage foreclosure procedure is a common example, because states typically regulate every step and leave no gap for local rules to fill.
Conflict Preemption
Obeying both laws at once is impossible. If a state law permits the sale of a product and a county ordinance bans it, no one can comply with both. The state law controls and the ordinance falls. The test is simultaneous compliance: if a person can follow both rules without contradiction, there is no conflict, and the local ordinance may survive.
When a County Ordinance Can Be Stricter
Preemption does not shut counties out of every subject the state has touched. In many areas, state law deliberately sets a minimum standard, a regulatory floor, and leaves counties free to go further. A stricter local rule does not conflict with a state minimum because anyone who follows the tougher county rule automatically satisfies the state requirement. No one is caught between the two.
Whether a county actually has that room depends on legislative intent. Some statutes include a savings clause that expressly preserves local authority to go stricter. Others contain the opposite: language forbidding local governments from exceeding the state standard, which turns the state rule into a ceiling instead of a floor. When the statute is silent, courts read context, and the answer varies by state and by subject. This is where preemption disputes most often end up in litigation.
Subjects States Commonly Preempt
State preemption has expanded significantly. As of 2019, 49 of 50 states had enacted express preemption in at least one policy area, with more than 250 individual instances across the country. A few of the most contested areas:
- Firearms. Roughly 45 states restrict local governments from passing their own gun laws, making state law the ceiling. Connecticut, Hawaii, Massachusetts, New Jersey, and New York allow more local discretion.
- Minimum wage. About half the states prohibit local governments from setting a minimum wage above the state or federal rate. A county in one of those states cannot respond to local cost-of-living pressure with a higher wage floor.
- Rent control. Approximately 32 states prohibit local rent control ordinances. Even a county facing an affordability crisis cannot cap rent increases if the state has foreclosed the option.
- Other subjects. States also commonly preempt local regulation of tobacco sales, anti-discrimination protections, certain zoning matters, and public health measures.
Personal Penalties on Local Officials
A newer form of preemption goes beyond invalidating conflicting ordinances and reaches the officials who pass them. Some states now impose civil fines on individual officials, allow removal from office, and prohibit the use of public funds for legal defense when local officials enact or enforce a preempted rule. Several states have adopted these measures in the firearms context, with penalties ranging from $1,000 to $50,000 depending on the state and whether it is a first offense.
The practical effect is a chilling one. Even in Home Rule counties, the risk of personal financial liability makes officials cautious about testing the edges of state authority, regardless of how confident they are that a proposed ordinance falls within local power.
What To Do If You Think a County Ordinance Is Preempted
This is where the analysis meets daily life, and where people most often get it wrong. A conflicting ordinance is not automatically void. It stays on the books, and it is enforceable, until a court says otherwise. You cannot ignore a local ordinance because you believe it conflicts with a state statute. If you violate it, you face the same fines or penalties as anyone else, and you will be litigating preemption from the harder position of a defendant.
The standard vehicle for challenging a preempted ordinance is a declaratory judgment action in state court. The court is asked to rule on the legal question of whether the ordinance is valid given the state statute, and if the court agrees the ordinance is preempted, the county can no longer enforce it. The state attorney general can sometimes bring or join such a challenge, and in some states any affected person or business has standing to sue.
Filing fees vary by jurisdiction and attorney fees for preemption litigation can be substantial, because the legal arguments are often technical. Before you comply, challenge, or ignore an ordinance you think is preempted, talk to an attorney who works in your state’s preemption framework. The rules turn on state-specific details, and the right move in one state is the wrong move in another.