Short answer
Federal law comes from the US national government; state law comes from a state. Both may apply to one person or activity. The Constitution makes valid federal law supreme when there is a genuine conflict, but that does not mean federal law addresses every issue or automatically erases all state rules. 1 2
Both can govern the same conduct; valid federal law takes priority where it conflicts with state law under the Supremacy Clause.
On this page
At a glance
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| Question | Federal law | State law |
|---|---|---|
| Source | US Constitution, Congress and authorized federal agencies | State constitution, legislature and state agencies |
| Geographic reach | Generally national within its subject and jurisdiction | Within the state, subject to constitutional limits |
| Conflict rule | Valid federal law can preempt conflicting state law | May operate alongside federal law where allowed |
The table summarizes the cited definitions and the article’s stated scope. 1 2
What each thing is
Federal law. Law of the United States under federal constitutional authority, including statutes and valid regulations. 1
State law. Law made by a US state under its own legal authority. 2
Key differences
The key is the government with authority to make the rule. Federal and state court systems also have different, sometimes overlapping jurisdiction. A legal problem can involve both bodies of law; deciding preemption requires the particular federal provision and state rule, not a slogan. 1 2
How to tell them apart
Identify the issuer and citation, then ask whether the federal government has authority over the subject and whether the rules actually conflict. A state licensing rule and a federal workplace rule may both apply. For a live dispute, use current law and professional advice. 1 2
Where they overlap
Both systems create enforceable rules and courts. Many everyday activities—employment, business, safety—are touched by both. 1 2
Edge cases
Federal law’s supremacy applies to valid federal law made under the Constitution; it is not a blanket claim that any federal statement overrides any state provision. States can sometimes offer additional protections when federal law permits them. 1 2
Why the distinction exists
The distinction follows US federalism, which divides and overlaps governing authority. It lets national rules coexist with state choices while providing a constitutional rule for genuine conflicts. 1 2
Common misconceptions
“Federal always wins” is too broad. The real question is whether valid federal law applies and displaces the specific state rule. 1 2
Examples
A company in California may need to meet a federal requirement and a California requirement. If a valid federal rule expressly or effectively preempts a conflicting state rule, the conflict is resolved under federal supremacy. 1 2
Sources
Sources checked October 3, 2026.
- Constitution Annotated / Library of Congress — U.S. Constitution, Article VI, Clause 2. Supremacy Clause text.
- U.S. Courts — Comparing Federal & State Courts. Jurisdiction comparison.