What Does It Mean to Repeal a Law? Repeal vs. Amendment, Sunset and Court Rulings

Last reviewed: October 5, 2026. This article is general information, not legal advice. It focuses on federal law; state rules on repeal and pending cases can differ, so check your state's statutes.

You've probably seen headlines saying lawmakers want to "repeal" a law, and wondered what that actually involves, and what happens to people already affected by it. This guide explains what it means to repeal a law, how that differs from amending a law, letting it expire, or a court striking it down, and what a repeal does to cases already in progress.

Short answer: To repeal a law means the legislature officially cancels it, so it no longer has legal force going forward. In the US, a federal law can only be repealed the same way it was made: Congress passes a new bill that removes it, and the President signs it (or Congress overrides a veto). Under the federal saving statute, a repeal generally doesn't erase penalties or liabilities incurred before it took effect, unless the repealing law says so.

Repeal, amendment, sunset and court rulings

These four are often mixed up, but they're legally different.

• Repeal. The legislature removes a law, in whole or in part, by passing a new law. An express repeal says so in words ("Section X is repealed"). An implied repeal happens when a later law is so inconsistent with an earlier one that both can't stand. Courts are reluctant to find implied repeals. As the Supreme Court put it in Posadas v. National City Bank (1936), "The cardinal rule is that repeals by implication are not favored."
• Amendment. The legislature changes the wording of a law but keeps it in force: adding a section, raising a fine, changing a deadline. A partial repeal is really a kind of amendment.
• Sunset (expiration). Some laws contain a "sunset clause" and simply expire on a set date unless renewed. No repeal vote is needed; lawmakers have to act to keep the law alive, not to end it.
• Court invalidation. A court can decide that a law is unconstitutional or conflicts with a higher law, and refuse to enforce it. That isn't a repeal: courts can't edit the statute books. The text usually remains on the books until the legislature removes it, which is why you sometimes hear about "unenforced" or "zombie" laws.

There's also a constitutional version. The Constitution can be changed only by a constitutional amendment, and one amendment can repeal another. The clearest example is the Twenty-first Amendment (1933), which states: "The eighteenth article of amendment to the Constitution of the United States is hereby repealed." That ended national Prohibition.

How Congress repeals a law

A repeal goes through the same process as any other bill:

1. Introduction. A member of the House or Senate introduces a bill that repeals the law (often alongside other changes).
2. Committee. The bill is sent to a committee for study. Most bills never get out of committee.
3. Floor votes. If released, it's debated and voted on. The House explains that a simple majority passes a bill in each chamber, although the Senate's procedural rules can make it harder to reach a final vote.
4. Same text in both chambers. The House and Senate must pass identical versions. Differences are worked out, then both chambers give final approval.
5. The President. The President can sign the bill or veto it. Under Article I, Section 7 of the Constitution, Congress can override a veto with a two-thirds vote in each house.

A president can't repeal a statute alone. Executive orders, on the other hand, can be revoked by a later president, and federal agencies can rescind their own regulations through the rulemaking process. Those are different tools from a repeal of a law passed by Congress.

At the state level, legislatures follow their own similar processes. In some states, voters can also repeal laws directly through a referendum or ballot initiative.

What happens to pending cases after a repeal?

This is where repeal gets practical. Suppose you were charged under a federal law, and Congress repeals it before your trial. Are you off the hook?

Generally, no. The federal saving statute, 1 U.S.C. § 109, says the old law is "treated as still remaining in force" for prosecuting penalties already incurred, unless the repealing law expressly says otherwise. In other words, the repeal looks forward, not back, unless Congress chooses differently.

Congress can choose differently, and courts look closely at what it intended. In Dorsey v. United States (2012), the Supreme Court considered the Fair Sentencing Act, which reduced crack cocaine penalties. The Court held that the Act's new, lower mandatory minimums applied to offenders who committed their crimes before the Act but were sentenced after it took effect. It explained that § 109 sets an important background rule, but a new law can override it "expressly or by necessary implication."

Two other federal rules are worth knowing:

• No automatic revival. Under 1 U.S.C. § 108, if Congress repeals a law that itself repealed an older law, the older law doesn't come back unless Congress expressly says so.
• Temporary laws. The second paragraph of § 109 applies the same "no release" rule to penalties incurred under a temporary statute that later expires.

Civil matters follow similar logic. Rights or obligations that already arose under the old law are often preserved, but the details depend on the repealing law's wording, so this is a question to raise with a lawyer if you're affected.

Why this matters to you

• If you're facing charges under a law that's been repealed or reduced, ask your lawyer whether the repealing law says anything about pending cases. That wording can make a real difference.
• If you're reading old laws online, check that they're still in force. A statute might have been repealed, amended, or held unconstitutional without the version you found being updated.
• If you're following a repeal effort, look for the effective date and any "transition" or "savings" clause in the bill.

To see where statutes fit in the overall hierarchy of US law, read our explainers on the "law of the land" and which article makes the Constitution the highest law.

Sources

• 1 U.S.C. § 109, Repeal of statutes as affecting existing liabilities: Cornell LII
• 1 U.S.C. § 108, Repeal of repealing act: Cornell LII
• Dorsey v. United States (2012): Cornell LII
• Posadas v. National City Bank of New York, 296 U.S. 497 (1936): Cornell LII
• U.S. Constitution, Article I, Section 7: National Archives transcript
• Twenty-first Amendment: National Archives
• U.S. House of Representatives, "The Legislative Process": house.gov