How courts interpret laws and rules

A law passed by the legislature and signed by the governor can still turn out to mean something different from what its sponsors said, or nothing at all. That is because courts get the last word on what a law means and whether it is valid. You do not need legal training to follow this. You need to know what courts do with laws, where their decisions are published and how to read one.

Judicial review

Since Marbury v. Madison (1803), American courts have claimed the power to refuse to enforce a law that conflicts with the Constitution. State courts do the same with state constitutions. This is judicial review. Courts do not go looking for laws to strike. Someone with a real stake has to bring a case, and the court decides the questions that case raises.

The practical lesson for a reader: the text in a code book is not always the law in force. Idaho has a vivid example.

How judges read a statute

When the words of a statute are disputed, judges use a fairly standard toolkit. Idaho wrote much of it into law in Idaho Code 73-113.

Two more ideas show up constantly. Courts try to read different sections so they fit together instead of conflicting. And when a specific provision and a general one collide, the specific one usually wins. When a court finds part of a law invalid, it also asks whether the rest can stand on its own, which is called severability. In Reclaim Idaho, the court restored the earlier version of the signature rule instead of leaving no rule at all.

Agencies, ambiguity and the end of Chevron

Agency rules raise a special question. When a statute is ambiguous, who decides what it means: the agency that administers it or the court?

For 40 years the federal answer was Chevron deference, from Chevron U.S.A. v. Natural Resources Defense Council (1984). If a statute was ambiguous and the agency's reading was reasonable, courts accepted it, even if a judge would have read the law differently.

On June 28, 2024, in Loper Bright Enterprises v. Raimondo, decided together with Relentless, Inc. v. Department of Commerce, the Supreme Court overruled Chevron. The vote was 6 to 3 in Relentless and 6 to 2 in Loper Bright, because Justice Jackson took no part in that case. Chief Justice Roberts wrote for the majority. The Court relied on section 706 of the Administrative Procedure Act, which tells reviewing courts to "decide all relevant questions of law." Courts must now use their own independent judgment to find the best reading of a statute, even an ambiguous one. Agency views still count: under the older Skidmore approach, an agency's interpretation can persuade a court depending on how thorough, well-reasoned and consistent it is. It just cannot control the outcome. Where Congress clearly delegates discretion to an agency, courts must respect the delegation and police its limits.

The Court also said past cases that upheld specific agency actions under Chevron keep their force through statutory stare decisis. Loper Bright did not wipe out existing rules.

Justice Kagan wrote the dissent, joined by Justice Sotomayor and, in the Relentless case, Justice Jackson. Her side argued that Congress has long expected agencies, with their technical staff, to fill gaps in complex statutes, and that the ruling shifts policy choices from experts accountable to the president toward judges. The majority answered that interpreting law is the core job of courts and that Chevron had become unworkable. Both positions are held by serious people. What is settled, as of October 2026, is the rule itself: federal courts no longer defer under Chevron.

Idaho moved first, by statute

Idaho changed its own rule for state agencies during its 2024 session, which ended before Loper Bright came down. The legislature amended Idaho Code 67-5279 to add subsection (5). When interpreting a state law or rule, an Idaho court "shall not defer to an agency's interpretation" and must decide the meaning de novo. And if doubt remains after all the usual tools, the court resolves it in favor of a reasonable interpretation "that limits agency power and maximizes individual liberty."

	Federal before June 2024 (Chevron)	Federal after Loper Bright	Idaho state agencies after 2024 amendment
Ambiguous statute, reasonable agency reading	Court accepts agency reading	Court decides best reading; agency view may persuade	Court decides de novo; no deference
Tie-breaker if doubt remains	Agency	None specified; court's best reading	Reading that limits agency power
Source of the rule	1984 Supreme Court case	2024 Supreme Court case interpreting APA section 706	Idaho Code 67-5279(5), 2024 Session Laws ch. 235

Reading an opinion

Opinions are published free: the U.S. Supreme Court at supremecourt.gov, the Idaho Supreme Court and Court of Appeals on isc.idaho.gov, federal appeals courts on their own sites. A U.S. Supreme Court opinion starts with a syllabus, a summary prepared by the Reporter of Decisions. It is the fastest way in, but it is not part of the opinion, so cite the opinion itself for anything that matters.

• Find the question. Opinions usually state the legal question in the first pages.
• Find the holding. Look for "We hold" or "we conclude." That sentence is the decision.
• Count the votes. Who joined the majority, who concurred and who dissented.
• Read the disposition. Affirmed, reversed, vacated, remanded. "Remanded" means the case goes back for more work, so the fight is often not over.
• Separate holding from commentary. Judges sometimes discuss issues they do not decide. Those passages, called dicta, do not bind later courts.