Conflicts between state and federal law show up most sharply in cannabis regulation, immigration enforcement, employee benefits, banking, minimum wage, product safety, and gambling. In each area, states have taken positions that either exceed, contradict, or refuse to support what federal law requires. Examples of conflict between state and federal law usually resolve in Washington’s favor under the Supremacy Clause, but the Tenth Amendment carves out real space that keeps many of these disputes alive.
The Constitutional Ground Rules
Article VI of the Constitution makes federal law, treaties, and the Constitution itself “the supreme law of the land,” binding on state judges regardless of what state law says.1Cornell Law School. Article VI U.S. Constitution Courts enforce that supremacy through preemption, which comes in three flavors: express preemption when Congress says so directly, field preemption when federal regulation is so complete that Congress is treated as the only regulator, and conflict preemption when following both laws is impossible or the state law obstructs federal goals.2LII / Legal Information Institute. Preemption
The Tenth Amendment pushes back. It reserves to the states any power not given to the federal government, and the Supreme Court has read it to prohibit Congress from “commandeering” state governments into running federal programs.3Constitution Annotated | Congress.gov | Library of Congress. Anti-Commandeering Doctrine That limit is why several of the conflicts below have lasted for years without a clean resolution.
Cannabis
Most states have legalized cannabis for medical use, adult use, or both. Federal law still classifies it as a Schedule I controlled substance, the category reserved for drugs the government considers to have high abuse potential and no accepted medical use.4Office of the Law Revision Counsel. 21 USC 812 Schedules of Controlled Substances Manufacturing, selling, and possessing cannabis remain federal crimes regardless of any state license.
A December 2025 executive order directed the Attorney General to expedite a pending rulemaking that would move cannabis to Schedule III, but as of early 2026 that process is not complete.5The White House. Increasing Medical Marijuana and Cannabidiol Research Every state-licensed cannabis operator currently runs afoul of federal drug law.
Banking Access
Banks with federal charters or federal deposit insurance carry anti-money-laundering obligations that make handling cannabis revenue extremely risky, since the money comes from an activity Congress has criminalized. Most state-licensed dispensaries operate almost entirely in cash as a result. That reality makes them robbery targets and complicates tax filings. The SAFE Banking Act, which would create a safe harbor for banks serving cannabis clients, has passed the House multiple times but has never cleared the Senate.
The Section 280E Tax Trap
Section 280E of the Internal Revenue Code bars any deduction or credit for expenses tied to trafficking in Schedule I or Schedule II drugs.6Office of the Law Revision Counsel. 26 U.S. Code 280E – Expenditures in Connection With the Illegal Sale of Drugs A cannabis retailer cannot deduct rent, payroll, or advertising the way any other business does. Only the direct cost of the product itself can be subtracted from gross income, which pushes effective tax rates on cannabis businesses to 70 percent or higher. Rescheduling to Schedule III would end 280E’s application to cannabis because the provision reaches only Schedule I and II substances.
Firearms and Cannabis Users
Under 18 U.S.C. § 922(g)(3), an “unlawful user of or addicted to any controlled substance” cannot possess firearms or ammunition.7Office of the Law Revision Counsel. 18 USC 922 Unlawful Acts A person who uses cannabis legally under state law is still an unlawful user for federal firearms purposes. The Supreme Court heard argument in United States v. Hemani in March 2026 on whether that ban is constitutional, with a decision expected by mid-2026.8Justia U.S. Supreme Court Center. United States v. Hemani
Wages and Employee Benefits
The Fair Labor Standards Act sets the federal minimum wage at $7.25 per hour, unchanged since 2009. Workers in a state with a higher minimum are entitled to the higher rate.9U.S. Department of Labor. Wages and the Fair Labor Standards Act The federal figure works as a floor rather than a ceiling, and most state rates in 2026 sit well above it, running roughly from $10.85 to nearly $17 per hour. This is the cooperative face of state-federal overlap: two systems set different numbers, and the more generous one governs.
Employee benefits are less cooperative. The Employee Retirement Income Security Act (ERISA) contains one of the broadest preemption clauses in federal law, overriding any state law that “relates to” a private employer-sponsored benefit plan.10Office of the Law Revision Counsel. 29 U.S. Code 1144 – Other Laws States generally cannot force private employers to offer health insurance, cannot regulate the benefits of self-insured employer plans, and cannot tax those plans. Even negligence claims against a health plan for a coverage denial have been preempted in many federal courts. For workers with employer-sponsored coverage, state consumer protections often do not apply.
Immigration and Sanctuary Policies
Immigration is a textbook field-preemption area. The Immigration and Nationality Act creates a complete regulatory scheme, and courts treat federal authority over who may enter, remain, or be removed as exclusive. In Arizona v. United States (2012), the Supreme Court invalidated several provisions of Arizona’s immigration enforcement statute because they intruded on that federal domain.
Sanctuary jurisdictions sit on the other side of the same coin. When a city or state refuses to detain people for federal immigration agents or share status information, it invokes the anti-commandeering doctrine: the federal government cannot conscript state officials into running federal programs. The result is a lopsided arrangement. States cannot build parallel immigration systems because the field is preempted, but they also cannot be ordered to work inside the federal one.
Transportation Safety
Federal transportation regulation leaves little room for state law, though the exact structure varies by mode.
Aviation and Drones
The Federal Aviation Act gives the FAA comprehensive authority over aviation safety and airspace, including pilot licensing, aircraft design, and operational rules. The FAA has asserted exclusive control over drone safety and airspace at any altitude.11Federal Aviation Administration. State and Local Regulation of Unmanned Aircraft Systems (UAS) Fact Sheet A locality can decide where a drone lifts off or lands as a land-use matter, but it cannot set its own altitude limits or equipment requirements.
Railroads
Federal railroad safety law preempts state law on any subject once the Secretary of Transportation issues a covering regulation. A state can adopt additional or stricter rules only if the rule addresses an essentially local safety hazard, does not conflict with federal law, and does not unreasonably burden interstate commerce.12Office of the Law Revision Counsel. 49 U.S. Code 20106 – Preemption Those conditions are difficult to meet, so federal standards dominate.
Motor Vehicles
Once a federal motor vehicle safety standard is in effect, states can only enforce identical standards. A savings clause preserves common-law liability, meaning a driver injured by a defective vehicle can still sue the manufacturer in state court.13Office of the Law Revision Counsel. 49 U.S. Code 30103 – Relationship to Other Laws The Supreme Court complicated that opening in Geier v. American Honda Motor Co. (2000), holding that a state tort claim requiring airbags was impliedly preempted because it conflicted with a federal standard that intentionally let manufacturers choose among passive restraint systems.14Justia U.S. Supreme Court Center. Geier v. American Honda Motor Co. 529 U.S. 861 (2000) Common-law claims survive in general, but a specific claim can still be preempted where it would override a deliberate federal choice.
FDA-Regulated Products
Class III medical devices, the highest-risk category that includes pacemakers and artificial hips, receive FDA premarket approval that carries preemptive force. Federal law bars states from imposing device requirements “different from, or in addition to” the federal ones.15Office of the Law Revision Counsel. 21 USC 360e Premarket Approval A state product-liability claim arguing an approved device should have been designed differently is typically preempted.
Prescription drug labeling works on similar logic. If the FDA has approved a specific label, a state law demanding different or contradictory warning language creates an impossible situation for the manufacturer, and impossibility preemption applies.16Federal Register. Preemption Review
Banking Under Federal Charter
National banks chartered under the National Bank Act operate under federal rules that displace much of state financial regulation. The Office of the Comptroller of the Currency has codified preemption of state-imposed interest rate caps, loan-to-value requirements, repayment term limits, and disclosure mandates for national banks.17eCFR. Subpart D Preemption
State laws of general application—contracts, torts, criminal law, debt collection, property, taxation, zoning—generally still reach national banks.17eCFR. Subpart D Preemption The dividing line runs between laws that regulate the bank’s core powers and laws that apply to everyone. A consumer’s state protection statute may govern a credit card from a state-chartered lender but not the same product from a national bank.
Nuclear Energy
The Atomic Energy Act of 1954 gives the Nuclear Regulatory Commission exclusive jurisdiction over the radiological safety aspects of nuclear power plant construction and operation. States keep authority over non-radiological questions such as whether the state needs the power, the plant’s economics, and non-radiation environmental impacts. Radiation exposure limits, reactor safety design, and radioactive waste handling belong entirely to the federal government, whether or not a state rule would actually conflict with a specific federal one.
Sports Betting and the Limit on Federal Power
The anti-commandeering doctrine has real teeth. In New York v. United States (1992), the Supreme Court struck down a federal law directing states to regulate radioactive waste. In Printz v. United States (1997), it invalidated Brady Act provisions requiring local law enforcement to conduct gun-buyer background checks.
The most consequential recent application came in Murphy v. National Collegiate Athletic Association (2018), which struck down a federal statute that prohibited states from authorizing sports betting.18Supreme Court of the United States. Murphy v. National Collegiate Athletic Assn. (May 14, 2018) The Court held that Congress cannot “dictate what a state legislature may and may not do,” and that forbidding a state to repeal its own gambling ban was as unconstitutional as compelling it to enact a new one. Within a few years, most states had legalized some form of sports betting.
That same doctrine explains why cannabis legalization, sanctuary policies, and other state departures from federal preferences continue. Congress can regulate individuals and businesses directly and attach conditions to federal funding, but it cannot draft state officials into enforcing federal law. That structural limit is what keeps these conflicts alive rather than settled.