Types of Primary Law in the US: The Complete Map (Statutes, Regs, Cases, and More)

Primary law is the law itself. Everything else is someone talking about it.

The citation that looked right and lost anyway

A junior associate hands you a memo. The argument rests on a case that is real, on point, and beautifully reasoned. It is also a California Court of Appeal decision, and the matter is in a Texas federal court applying Texas law. The case exists. The reasoning is sound. And it binds no one in the room.

That is the trap that the phrase "primary law" hides. Knowing a source is the law is only half the question. The other half is whether that particular slice of law has any hold over your court, your jurisdiction, and your facts. Get the category right and the source wrong, and you have cited authority that a judge is free to ignore.

Short answer: primary law is law issued by a government body with the power to make it, and in the US it comes in eight forms: constitutions, statutes and codes, regulations, case law, court rules, executive actions, treaties, and local ordinances. Whether any given piece of it actually binds a court is a separate test (mandatory versus persuasive), and whether it is still in force is a third (is it good law). This guide is the whole map, plus the two tests that decide if a source helps you or sinks you.

TL;DR

• Primary law is the law itself. Secondary sources (treatises, law reviews, Restatements, encyclopedias) explain the law but are never binding. A brilliant law-review article loses to a mediocre statute every time.
• There are eight types of US primary law: constitutions, statutes, regulations, case law, court rules, executive actions, treaties, and local ordinances. Most guides list four and stop at case law.
• Primary does not mean binding. Only primary law can be mandatory, but plenty of it is merely persuasive. An out-of-jurisdiction statute or a sister-circuit opinion is primary law and still optional for your court.
• The US Code has a wrinkle most people miss. Only 27 of its titles are enacted as "positive law." For the rest, the title is prima facie evidence, and the Statutes at Large controls if the two ever disagree.
• Currency is a third, separate test. A section can be real, on point, and repealed. Reading the text is not enough; you check whether it is still good law.

Part of our state law reference series. For the companion pieces, see how AI legal research works and searching US statutes and regulations for the current version.

Primary versus secondary: the law versus the commentary about it

Every source you can cite falls on one side of a line. On one side is primary authority: the actual law, issued by a body with the constitutional power to make it. On the other is secondary authority: everything written about the law by people who do not make it. Treatises, Restatements, law-review articles, A.L.R. annotations, hornbooks, and legal encyclopedias are all secondary.

The rule that follows is short and absolute. Secondary authority is always persuasive and never binding, as law-school research guides put it plainly (Chapman University Law Library). You cite a treatise to explain a doctrine or to fill a gap where no primary law is on point. You never cite it as the thing a court must follow. A judge who disagrees with the most respected treatise in the field is free to disagree, and nothing happens.

So the first cut is easy: is this the law, or is it someone's account of the law? The harder question comes next.

The test that actually matters: mandatory or persuasive

Here is the distinction that the associate's memo missed. Being primary law does not make a source binding. Only primary authority can be mandatory, but not all primary authority is mandatory. Whether a given piece binds a court depends on which jurisdiction issued it and on where the deciding court sits in the hierarchy above it.

A Ninth Circuit ruling binds the district courts inside the Ninth Circuit and only nudges a court in the Fifth, because binding effect turns on the jurisdiction that issued the law and the deciding court's place beneath it. A sister state's highest court, however well reasoned, is a suggestion. This is why "find me a case that says X" is a dangerous instruction: a case that says X but comes from the wrong court reads as authority while carrying none.

One qualifier saves this from being a rule of thumb that misfires. Forum is not the same as governing law. A federal court sitting in diversity, or any court running a choice-of-law analysis, may have to apply another state's substantive law. When it does, that state's statutes and high-court decisions become the law to apply, even though the court sits elsewhere. So the real question is never just "where is this court," it is "whose law governs this issue, and what does the hierarchy of that jurisdiction say."

Here is the same logic as a worked example, with the twist that trips people up. Say a contract dispute lands in the Southern District of New York on diversity jurisdiction, and the contract has a Delaware choice-of-law clause. The court is federal and sits in New York, but Delaware substantive law governs the contract. Five sources are on your desk, and the binding column tracks Delaware, not New York:

The court sits in New York and the controlling law is from Delaware, which is the whole point: forum tells you where you are, governing law tells you what to cite. Two of the five bind, two are federal courts guessing at Delaware law, one is a treatise, and each still needs a currency check before you rely on it. Telling them apart is the entire skill.

The eight types of US primary law

Most explainers list four categories and stop. The full map has eight, and the ones that get left off (court rules, executive actions, treaties, ordinances) are exactly the ones that surprise people mid-matter.

Constitutions

The US Constitution sits at the top: seven Articles and 27 Amendments that set the structure of government and the outer limits of what any other law may do. Under the Supremacy Clause of Article VI, the Constitution, federal laws made pursuant to it, and treaties are "the supreme Law of the Land" (Cornell Legal Information Institute). A statute or regulation that conflicts with the Constitution is void.

Then there are 50 state constitutions, plus those of DC and the territories. A state constitution can grant more protection than the federal one, never less. State high courts routinely read their own constitutions to exceed the federal floor on search and seizure, free speech, and privacy. If you only checked the US Constitution, you checked the minimum.

Statutes and codes

Statutes are laws passed by a legislature. At the federal level they are compiled into the United States Code, organized into 53 subject titles (Titles 1 through 52 plus 54, with Title 53 held in reserve). Every state has its own codified statutes, from the California Codes to the New York Consolidated Laws.

Only some US Code titles are "positive law," and the difference occasionally decides a case. Congress has enacted 27 of the 53 titles into positive law, meaning the title itself is the legal evidence of the statute (Library of Congress). For the other titles, the Code is only prima facie evidence of the law, and if the printed Code ever disagrees with the Statutes at Large (the chronological record of what Congress actually passed), the Statutes at Large wins. Most of the time it does not matter. When it does, it decides the case.

Regulations and administrative codes

Legislatures write broadly and hand the detail to agencies. Those agencies issue regulations, which carry the force of law as long as they stay within the authority the statute delegated. Federal regulations are published first in the daily Federal Register, then compiled into the Code of Federal Regulations, organized into 50 titles. States run the same two-layer system with their own registers and administrative codes.

Regulations are primary law, but their footing shifted recently. In 2024 the Supreme Court's decision in Loper Bright Enterprises v. Raimondo ended Chevron deference, so courts no longer defer to an agency's reading of an ambiguous statute and instead decide the best reading themselves. A regulation that survived on deference for years can be read differently now. That is a currency problem hiding inside a category, and it is the kind of thing a stale answer will never tell you.

Case law

Courts decide cases, and their written opinions interpret every category above. A published appellate opinion is binding precedent on lower courts within its own hierarchy. An unpublished opinion is a different animal: under Federal Rule of Appellate Procedure 32.1, courts may not forbid citing unpublished federal opinions issued on or after January 1, 2007 (Cornell Legal Information Institute), but "citable" is not "precedential." Its weight varies by circuit, and you flag it as unpublished when you cite it.

One thing that often gets grouped here does not belong: dockets. The docket is the litigation record, the filings and orders in a live case. It is primary source material for what is happening in a matter, and it is invaluable, but a party's brief is not law and binds no one. Dockets are primary records, not a type of primary authority.

Court rules

The rules of procedure are primary law that governs how litigation runs: the Federal Rules of Civil Procedure, Criminal Procedure, Evidence, Appellate Procedure, and Bankruptcy Procedure, plus each state's and each court's own local rules. Miss a deadline in the rules and the merits never get heard. These rarely make the "types of primary law" lists, and they decide cases constantly.

Executive actions

The President issues Executive Orders, Proclamations, and Presidential Memoranda. These are primary law within the executive branch's authority. They are published in the Federal Register and compiled annually into Title 3 of the CFR. An executive order can reshape agency behavior overnight, and it can be revoked just as fast by the next order, which makes this the most volatile category on the map.

Treaties

Treaties made under the authority of the United States are, alongside the Constitution and federal statutes, part of the supreme law of the land under Article VI. Two nuances matter. A treaty and a federal statute sit on equal footing, so when they conflict the later in time controls, not the treaty automatically. And treaties come in two kinds: a self-executing treaty operates as domestic law on its own, while a non-self-executing treaty needs implementing legislation before a court will enforce it. Most matters never touch a treaty. The ones that do (trade, extradition, cross-border disputes) cannot be answered without one.

Local ordinances

At the bottom of the pyramid by scope, but binding where they apply, are the ordinances of cities and counties: zoning codes, health codes, business-licensing rules, noise ordinances. They are primary law for anyone operating in that municipality, and they are the layer most likely to be missing from a national database.

The hierarchy, in one picture

When two pieces of primary law conflict, a fixed order decides which controls. The Constitution sits at the top. Federal statutes and treaties come next, on equal footing with each other, with the later of the two controlling when they clash. Regulations sit under the statutes that authorize them, and federal law preempts conflicting state law under the Supremacy Clause. Courts sit alongside this stack, interpreting each layer and binding the courts below them.

The part that ages: is it still good law?

Every category above shares one weakness. It changes. Statutes get amended and repealed. Regulations get revised and rescinded. Opinions get overruled, superseded by statute, or quietly abrogated by a later decision. An executive order is one signature from gone.

This is a third test, independent of the first two. A source can be primary (test one), mandatory in your jurisdiction (test two), and dead (test three). The section you are reading might have been amended last month. The case you are citing might have been overruled last year. Reading the text tells you what it says, not whether it still applies. That is why lawyers check treatment: KeyCite and Shepard's for cases, effective-date and amendment history for statutes and regulations. We wrote a full walkthrough of that check for statutes in is the section still current.

Why a quick search or an AI answer is not enough

Type a legal question into a general chatbot and you get a fluent paragraph with no category, no jurisdiction, and no date. It cannot tell you whether the rule it stated is a binding statute or a persuasive out-of-state case, and it certainly cannot tell you whether the version it half-remembers from training data is the version in force today. That is how confident, wrong answers get filed. We laid out the mechanics of that failure in grounding versus guessing.

A smarter guess does not solve this. Retrieval against the actual primary law does, with a citation and a link back to the official source on every claim, so you can see the category and open the text yourself. That is the shape of how AI legal research works when it is built to be checked.

This is the ground Vaquill AI is built on. The research product answers questions against US case law and the full statutory corpus, and every answer runs through a four-layer citation-verification pipeline that flags anything it cannot confirm against the source. For developers who want the primary law directly, the statutes and regulations API returns sections from the US Code, the CFR, all 50 state codes, the US Constitution, the Federal Rules, state constitutions and court rules, and executive actions, each with a citation and a link to the official government text. That public API is statutes and legislation only; case-law research lives in the product, not the API. Both draw on the same corpus, refreshed monthly.

FAQ

What are the types of primary law in the US?

Eight: constitutions (federal and state), statutes and codes, regulations and administrative codes, case law, court rules, executive actions (Executive Orders, Proclamations, and Memoranda), treaties, and local ordinances. Each is issued by a government body with the authority to make it. Most short explainers list only the first four. (Dockets and court filings are useful primary records, but a filing is not binding law, so they are not a type of primary authority.)

What is the difference between primary and secondary authority?

Primary authority is the law itself, issued by a government body: constitutions, statutes, regulations, cases, rules, and the rest. Secondary authority is commentary about the law, such as treatises, Restatements, law-review articles, and legal encyclopedias. Primary law can be binding on a court. Secondary authority is always persuasive and never binding, no matter how respected the author.

Is a statute always binding?

No. A statute is primary law, but it binds only the courts of the jurisdiction that enacted it. Your own state's statute is mandatory in your state's courts. Another state's statute, though still primary law, is only persuasive. Primary does not mean mandatory; jurisdiction and court hierarchy decide.

Can you cite an unpublished court opinion?

For federal appellate opinions issued on or after January 1, 2007, yes. Federal Rule of Appellate Procedure 32.1 bars courts from prohibiting their citation. But an unpublished opinion is non-precedential, its weight varies by circuit, and you identify it as unpublished when you cite it. It is citable, not controlling.

Are executive orders primary law?

Yes. Executive Orders, Proclamations, and Presidential Memoranda are primary law within the executive branch's authority. They are published in the Federal Register and compiled in Title 3 of the Code of Federal Regulations. They are also the most volatile category, since a later order can revoke an earlier one immediately.

How do I know if a statute or case is still good law?

Reading the text is not enough, because it does not tell you whether the source has been amended, repealed, overruled, or superseded. Check its treatment: KeyCite or Shepard's for a case, and amendment and effective-date history for a statute or regulation. A source can be real, on point, and no longer in force, which is the error that reading alone will never catch.

Priyansh Khodiyar

Co-Founder & CTO

Priyansh leads engineering and AI at Vaquill, from the matter workbench to drafting, document comparison, document matrix, and citation-verified research.