No, states cannot ignore federal law in the sense of nullifying it or declaring it inoperative within their borders. The Supremacy Clause of the U.S. Constitution makes federal law binding on every state judge, and no state has ever successfully overridden a valid federal statute. But the question of whether states can ignore federal law has a more textured answer than that flat “no” suggests. States keep broad authority in areas the Constitution reserves to them, the federal government cannot force state officials to enforce federal programs, and many federal laws deliberately let states go further than the federal baseline. The result is a system where state resistance to federal policy is common and often lawful, even though outright nullification is not.
Why Federal Law Wins When It Conflicts With State Law
Article VI of the Constitution declares that the Constitution, federal laws made under its authority, and treaties are the “supreme Law of the Land,” and that judges in every state are bound by them regardless of anything in their own state’s constitution or statutes.1Legal Information Institute. Article VI, U.S. Constitution When a valid federal law and a state law conflict, the state law is displaced through a doctrine called preemption.
Preemption comes in two forms. Express preemption is when Congress writes directly into a statute that federal law overrides state law on the same subject. Implied preemption is trickier. It applies when complying with both laws is impossible, when a state law would obstruct a federal objective, or when Congress has regulated an area so thoroughly that no room remains for state rules. Immigration is the clearest example of the last category. In Arizona v. United States (2012), the Supreme Court struck down three provisions of an Arizona immigration enforcement law because the federal government’s comprehensive regulation of immigration left no space for states to create their own penalties or enforcement mechanisms.2Justia Law. Arizona v. United States, 567 U.S. 387 (2012)
So if a state passed a law saying federal immigration statutes do not apply within its borders, that law would be struck down. That is nullification, and nullification is not a legal option.
Where States Keep Their Own Authority
Federal power is not unlimited. The Tenth Amendment says powers not granted to the federal government by the Constitution, and not prohibited to the states, belong to the states or the people.3Legal Information Institute. Tenth Amendment, U.S. Constitution This is the basis for the “police powers” that let states regulate the health, safety, and welfare of their residents.
Most of the law that touches everyday life sits in this state-controlled space: family law, education, property rights, professional licensing, local criminal enforcement, and the structure of local government. The federal government generally cannot override state choices in these areas unless it can tie its action to a specific constitutional power like the Commerce Clause or the taxing power. When it can make that connection, the Supremacy Clause takes over. When it cannot, the Tenth Amendment leaves the space to the states.
What States Can Do That Looks Like Ignoring Federal Law
Even where federal law clearly applies, a state has more room to push back than a strict reading of the Supremacy Clause suggests. Two mechanisms do most of the work.
Declining to Help Enforce Federal Law
The federal government cannot force state officials to carry out federal programs. The Supreme Court has built a strong anti-commandeering doctrine around this idea. In New York v. United States (1992), the Court held that Congress “may not compel the States to enact or administer a federal regulatory program” when it struck down a law requiring states to regulate radioactive waste on federal terms or take ownership of it.4Legal Information Institute. New York v. United States, 505 U.S. 144 (1992) Five years later, Printz v. United States (1997) struck down a Brady Act provision that required local law enforcement to conduct federal background checks on gun buyers, holding that Congress cannot conscript state and local officers to run a federal program.5Legal Information Institute. Printz v. United States, 521 U.S. 898 (1997) Murphy v. NCAA (2018) extended the same logic to prohibitions: telling states they cannot legalize sports gambling was just as much commandeering as telling them they must regulate.
This is the legal foundation for “sanctuary” policies. When a city or state directs its police not to help federal immigration agents, it is not nullifying federal immigration law. Federal agents can still enforce that law themselves. The state is declining to volunteer its resources. State marijuana legalization works the same way. A majority of states allow medical or recreational cannabis as of 2026, even though marijuana remains a Schedule I controlled substance federally. A proposed rescheduling to Schedule III has been pending since May 2024, and a December 2025 executive order directed the Attorney General to complete rescheduling as quickly as possible, though no final rule has been published.6The White House. Increasing Medical Marijuana and Cannabidiol Research State legalization and federal prohibition coexist because federal authorities have not aggressively enforced the federal ban, not because state law has displaced it.
Going Further Than Federal Law Allows
Many federal statutes set a floor rather than a ceiling. They establish a minimum standard and let states enact stricter rules on top of it. The Clean Air Act says nothing in the act prevents a state from adopting stricter emission standards or pollution controls than the federal government requires; the only prohibition runs the other way, against weaker state standards.7Office of the Law Revision Counsel. 42 U.S.C. 7416 – Retention of State Authority The Fair Labor Standards Act sets the federal minimum wage at $7.25 per hour but explicitly provides that nothing in the statute excuses noncompliance with any state or local law that establishes a higher one.8Office of the Law Revision Counsel. 29 U.S. Code 218 – Relation to Other Laws As of January 2026, roughly 30 states enforce minimum wages above the federal rate.9U.S. Department of Labor. State Minimum Wage Laws
Recognizing whether a federal statute functions as a floor or a ceiling matters. If you assume the federal rule blocks all state regulation on a topic, you might overlook stronger state protections that actually apply to you.
What It Means for You When State and Federal Law Disagree
The gap between state legality and federal prohibition is not just an abstract question. The Supreme Court made the personal exposure clear in Gonzales v. Raich (2005), holding that Congress has the power under the Commerce Clause to prohibit marijuana cultivation and use even when it occurs entirely within a state that has legalized it.10Justia Law. Gonzales v. Raich, 545 U.S. 1 (2005) Following state law does not create a defense to federal prosecution. Federal authorities rarely pursue individual users, but the legal risk exists.
Financial consequences hit more people. Because marijuana remains federally illegal, banks and credit unions risk anti-money-laundering violations by handling cannabis proceeds, and major financial institutions and card networks largely refuse to serve cannabis businesses. State-licensed dispensaries often operate cash-only, without business bank accounts, loans, or electronic payment processing. Federal deposit insurance does not cover cannabis-related transactions.
Employment adds another layer. Federal contractors with contracts of $100,000 or more must maintain a drug-free workplace under the Drug-Free Workplace Act of 1988, which requires policies prohibiting controlled substances in the workplace and mandates consequences for violations.11SAMHSA. Federal Contractors and Grantees If you work for a federal contractor or hold a security clearance, state-legal marijuana use can cost you your job even if you never use it at work. Federal civil forfeiture statutes and the federal equitable sharing program can also reach property tied to activity that is legal under state law.
How State-Federal Conflicts Actually Get Resolved
Disputes over which law wins are resolved in the federal court system, with the U.S. Supreme Court as the final arbiter. A state law can be challenged as preempted by the federal government, by private parties caught between conflicting rules, or by states seeking clarity. If a federal court finds a state law is preempted, it can enjoin the state from enforcing it. In 2025, the Attorney General directed the Civil Division to identify and challenge state and local laws that conflict with federal immigration law, prioritizing “affirmative litigation to invalidate any State or local laws preempted by Federal law.”12Department of Justice. CIV Enforcement Memo
Congress also has a non-litigation tool: the spending power. It can attach conditions to federal funds to pressure states into policies it could not directly mandate. Under 23 U.S.C. ยง 158, the federal government withholds highway funding from any state that allows people under 21 to purchase or publicly possess alcohol, at 5 percent in the first year of noncompliance and 10 percent each year after.13Office of the Law Revision Counsel. 23 U.S.C. 158 – National Minimum Drinking Age The Supreme Court upheld this approach in South Dakota v. Dole (1987), allowing Congress to condition federal spending on state policy choices as long as the conditions relate to the funding’s purpose and are not so coercive that they compel rather than encourage.14Justia Law. South Dakota v. Dole, 483 U.S. 203 (1987) Every state eventually adopted the 21-year-old drinking age.
The spending power has limits. In NFIB v. Sebelius (2012), the Court held that Congress went too far when it threatened to strip all existing Medicaid funding from states that refused to expand the program under the Affordable Care Act. Withdrawing funding that states already depend on looked less like an incentive and more like coercion. That line, between encouragement and compulsion, is where the tool’s constitutional boundary sits.
So a state cannot legally ignore a federal law it disagrees with. It can, however, refuse to enforce that law with its own officers, legalize under state law what federal law prohibits, and regulate more strictly than the federal government does. Those choices are lawful. Nullification is not.