State Law vs Federal Law, Which Wins When They Conflict? 2026
What You Need to Know Right Now
When state law and federal law conflict, federal law displaces, or preempts, state law, due to the Supremacy Clause of the Constitution. Here’s the truth: a state statute is void to the extent that it actually conflicts with a valid Federal statute. Bottom line: federal law wins—but only if Congress acted within its constitutional powers.
Why This Matters to You
State-federal conflicts affect your daily life more than you realize. Cannabis is legal in your state but federally illegal. Your state minimum wage exceeds the federal rate. Your state protects abortion access while federal law remains uncertain.
The Trump administration filed a new federal lawsuit challenging Illinois’s law under the supremacy clause in early 2026. This shows how state-federal battles directly impact which laws you must follow.
Most sites won’t tell you this, but: you can be prosecuted under federal law even when complying with state law. Even people who grow or have marijuana in the amounts allowed by their state can be arrested and prosecuted by the federal government.
What You Came to Know: How State-Federal Conflicts Work
The Supremacy Clause: Federal Law’s Constitutional Authority
The Supremacy Clause, found in Article VI of the Constitution, says that federal laws are more important than state laws. The exact text reads: “This Constitution, and the Laws of the United States which shall be made in Pursuance thereof…shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby”.
Here’s what that actually means for you: the Constitution and federal laws take priority over any conflicting rules of state law.
Three Types of Federal Preemption
Federal law can override state law in three distinct ways.
Express Preemption: Federal law can expressly preempt state law when a federal statute or regulation contains explicit preemptive language. Congress literally states in the law that federal rules control.
Example: The Immigration Reform and Control Act of 1986 contained an express preemption clause, codified at 8 U.S.C. § 1324(h)(2), which the Supreme Court used to strike down Arizona’s immigration penalties.
Field Preemption: Field preemption occurs where federal law is so pervasive as to make reasonable the inference that Congress left no room for the States to supplement it, or where the federal interest is so dominant.
Example: The Supreme Court held that federal Occupational Safety and Health Administration (OSHA) regulations preempted Illinois laws on workers handling hazardous material because federal law completely occupied workplace safety regulation.
Conflict Preemption: Conflict preemption occurs where compliance with both federal and state law is impossible (impossibility preemption) or where state law poses an obstacle to federal objectives (obstacle preemption).
Example: In Sperry v. Florida, the Supreme Court examined a conflict between federal patent laws and a state law governing the licensure of attorneys. The Court ruled that federal law preempted state law with regard to the person’s ability to act as a patent agent in Florida.
Real-World Examples of State-Federal Conflicts in 2026
Cannabis Legalization: Some states allow people to use marijuana for fun or for medical reasons, but it is still illegal under federal law. Businesses that sell marijuana legally in their state cannot open bank accounts or accept credit cards because banks are not allowed to do business with them under federal law.
Environmental Protection: Louisiana parishes filed lawsuits in state court against oil and gas companies, seeking to hold them liable for World War II-era crude oil production that allegedly harmed the coast. In April 2025, a Louisiana jury ruled Chevron must pay almost $745 million. Chevron argues federal preemption should move the case to federal court.
Immigration Enforcement: Minnesota enacted laws holding federal officers accountable for constitutional violations, prompting federal lawsuits challenging state authority under the supremacy clause.
Minimum Wage: States can set higher minimum wages than federal law because federal law establishes a floor, not a ceiling. While states may make their own laws, they must meet or exceed the federal standard.
How Courts Decide Which Law Applies
A state law will be found to violate the Supremacy Clause when either of the following two conditions (or both) exist: Compliance with both the Federal and State laws is impossible, or state law stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress.
Let’s break this down: If you can follow both laws simultaneously, courts might allow state law to stand. If following state law makes it impossible to comply with federal law, federal law wins.
What You Must Know
States Can’t Nullify Federal Law
The Eighth Circuit struck down Missouri’s Second Amendment Preservation Act (SAPA), which attempted to declare federal gun laws “invalid” in Missouri and prohibited state cooperation with federal firearms enforcement. The court ruled Missouri cannot nullify federal law.
Here’s what that actually means for you: your state can refuse to help enforce federal law, but it can’t declare federal law void or punish you for complying with it.
Federal Law Must Be Constitutional
Federal statutes and treaties must be within the parameters of the Constitution; that is, they must be pursuant to the federal government’s enumerated powers.
If Congress acts beyond its constitutional authority, courts can strike down the federal law—even if it conflicts with state law.
2026 Supreme Court Cases Reshaping State-Federal Balance
Several pending cases will determine the future of state-federal conflicts:
- Trump v. Slaughter: The Court is considering whether Congress had the power to limit the reasons the president could remove a commissioner in the Federal Trade Commission Act, with broader implications for independent agencies.
- Illinois Election Law: Illinois currently allows election officials to count mail-in ballots received up to two weeks after Election Day so long as the ballots are postmarked by that date. The Supreme Court is reviewing whether federal law preempts this practice.
- Louisiana Environmental Case: Chevron claims that its history as a federal contractor during World War II entitles it to federal jurisdiction, a legal maneuver widely criticized as a stalling tactic aimed at dodging a $740 million judgment.
What to Do Next
Identify Which Laws Apply to Your Situation
Check both state and federal requirements. Assume you must comply with whichever is stricter unless federal law expressly preempts state law.
Document Your Compliance Efforts
Keep records showing you attempted to follow both state and federal law. If prosecuted, this evidence demonstrates good faith.
Consult an Attorney When Laws Clearly Conflict
If state law requires one action and federal law prohibits it, legal counsel can assess your risks and options.
💡 Pro Tip: When state and federal law conflict, research whether federal agencies are actively enforcing the federal law in your state. Federal marijuana prohibition exists nationwide, but enforcement priorities vary dramatically by administration and region—dramatically affecting your practical risk.
Frequently Asked Questions
Can state law override federal law?
No. Federal laws always prevail over state laws. This helps to avoid conflicts between state and federal laws and keeps the United States, well, united.
What is the Supremacy Clause?
The Supremacy Clause refers to the foundational principle that, in general, federal law takes precedence over any conflicting state law. Established under Article VI, Paragraph 2 of the U.S. Constitution.
Can I be prosecuted under both state and federal law for the same act?
Yes. Preemption applies regardless of whether the conflicting laws come from legislatures, courts, administrative agencies, or constitutions. Separate sovereigns can prosecute separately.
What happens if I follow state law but violate federal law?
You’re still violating federal law. The Court also cautioned that, when evaluating evidence of Congressional intent, courts should err on the side of state rather than federal authority—but this only matters in close cases where preemption is unclear.
Can states refuse to enforce federal law?
Under the “anti-commandeering” doctrine, Congress cannot compel state legislatures to enact specific legislation or conscript state officers to enforce federal laws. States can decline to help, but they can’t obstruct federal enforcement.
Does federal law always win?
Almost always. Whether express or implied, federal law will almost always prevail when it interferes or conflicts with state law. Unless the U.S. Supreme Court declares the federal law unconstitutional.
What should businesses do when state and federal laws conflict?
Comply with both if possible. If impossible, prioritize federal law to avoid federal prosecution. Consider purchasing insurance for regulatory compliance violations.
Take Action
Review both state and federal requirements affecting your situation. For constitutional questions, visit Congress.gov for federal statutes or consult the U.S. Constitution Supremacy Clause for authoritative analysis.
Need help understanding federal legal protections? Learn about What Is The Supreme Law Of The Land to understand constitutional hierarchy.
Last Updated: February 7, 2026
This article provides general legal information and is not legal advice. For specific questions about state-federal law conflicts in your situation, consult a qualified attorney.
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About the Author
Sarah Klein, JD, is a licensed attorney and legal content strategist with over 12 years of experience across civil, criminal, family, and regulatory law. At All About Lawyer, she covers a wide range of legal topics — from high-profile lawsuits and courtroom stories to state traffic laws and everyday legal questions — all with a focus on accuracy, clarity, and public understanding.
Her writing blends real legal insight with plain-English explanations, helping readers stay informed and legally aware.
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