US Law Data: The Complete Guide for Business and Technical Readers

Short answer: US law data is the text of the law in a form you can search, store and build on. That covers statutes (laws passed by a legislature), regulations (rules written by government agencies), court rules (the procedures courts set), agency guidance (an agency's explanation of its own rules), attorney general opinions (a state's top lawyer answering what a law means) and court decisions. Most of it is published free by governments, but every publisher does it differently. This page is the map. Pick your question below and follow the guide that answers it.

TL;DR

• US law is published in pieces. Congress, 50 states, hundreds of agencies and the courts each publish their own, in their own format.
• The hard parts are not finding text. They are knowing which version is current, whether a copy is official, and how a bill, a session law and a code section relate.
• Start with the basics if the vocabulary is new. The first group below needs no legal background.
• Choosing a supplier or deciding whether to collect it yourself? The second group is a checklist and a fair comparison.
• Need the law on one topic? The third group reads the actual statutes for you, with citations.

Who uses US law data

Some readers pay for legal data: founders, product leads, compliance and legal operations heads. Some work with it: engineers and analysts. Many are simply trying to find out what a law says. The guides are tagged by reader, and most need no code.

One law, three places

A single law shows up in three forms, and the guides below keep returning to this. Take the TAKE IT DOWN Act, passed in 2025.

1. The bill. It started as Senate bill S. 146, a proposal. It was introduced in January 2025 and signed on May 19, 2025.
2. The session law. Once signed, it was published as it passed, as Public Law 119-12.
3. The code. Parts of it were then merged into the organized US Code. One part became 47 U.S.C. § 223a.

A tracker for bills shows the first. A publisher of the code shows the third. Each one answers a different question, and mixing them up is the most common mistake in legal data. The full trace is in How to Track Legislation: Bills vs. Laws, Explained.

Before you rely on any source

Whatever you use, check these six things. They apply to a free government site and a paid supplier alike.

1. Is it the official copy? Does the publisher say its text is the official version?
2. Is it current? Does the page show a date, and what does that date actually mean?
3. Is the citation form right? States and agencies cite differently.
4. How long until a change appears? Laws change on the publisher's schedule, not yours.
5. Can you read an older version? Some work needs the text as it stood on a past date.
6. What may you do with it? Licence terms decide whether you can show the text to your own customers.

Start here: the basics

If words like statute, regulation or session law are new, read these first, in this order.

1. Primary Law Explained for People Who Do Not Read Statutes shows the whole map once, using overtime pay as the running example. It covers constitutions, statutes, regulations, court rules, guidance and court decisions, and what "binding" means.
2. What Is a Regulation? How It Differs From a Statute explains who writes each and which one you are actually bound by.
3. What Is a Session Law? How It Differs From the Code explains why a law is published twice, and why the second copy can differ from the first.
4. How to Cite a Statute or Regulation in Plain English teaches you to read a citation like an address.
5. For the longer version of the same map, see Types of Primary Law in the US.

More basics, each with a real example traced from official sources:

• How Does a Bill Become a Law? From Idea to the US Code follows a federal bill and a Texas bill all the way into the code, and compares how six states differ.
• USC vs CFR: What the Abbreviations Mean and How They Differ decodes the two citations you see most.
• What Does Codified Mean in Law? explains why a law is merged into a code and what changes when it is.
• Federal vs State Law: Which One Applies to You covers who makes which law and what happens when both apply.
• What Is an Administrative Agency and What Does It Do? explains where agencies get their power.
• Notice and Comment Rulemaking follows one federal rule from proposal to the CFR.
• State Register vs. Administrative Code shows where states publish proposed and final rules.

Choosing where your legal data comes from

If you build or buy a product that has to be right about the law, these four guides are the decision path.

• What Is Legal Data? A Buyer's Guide to Types, Sources and Cost separates the kinds of legal data, who publishes each, and what drives the price.
• Ten Questions to Ask a Legal Data Vendor Before You Buy is a checklist. Each question has a good answer and a weak answer, so you can compare suppliers on the same terms.
• Build vs Buy Legal Data: Where Your Product's Law Should Come From lays out the costs and risks of each route evenly and does not tell you which to pick.
• Legal Data Provenance and Legal Data Freshness cover two things to ask any supplier: where each text came from, and how current it really is.

Reading the law on a topic

These guides read the statute text itself, quote it, and link the official source. They are written for business readers.

These topics change quickly. Each guide says what it checked and when, and tells you how to confirm the current text yourself.

Attorney general opinions

A state attorney general opinion is a written answer to a question about what state law means. It is not a statute, and it is not always binding, but it is often the only guidance that exists on a question no court has reached. They are scattered across 50 state websites.

• Attorney General Opinions by State: How to Find Them and What They Are Worth is the national guide.
• State guides that explain each state's own rules: Alabama, Arkansas, California, Florida, Kansas, Louisiana, Mississippi, Ohio and Texas. The rules really do differ, for example on how opinions are numbered, who may ask, and whether an official is protected for following one.

Following a law before and after it passes

Tracking legislation and knowing the current law are different jobs.

• How to Track Legislation: Bills vs. Laws, Explained follows one real bill from introduction into the code.
• For the tools that track bills, see the LegiScan API Guide, the Open States API Guide and the Congress.gov API Guide.
• For the rulemaking record that sits between a proposal and a final rule, see the Regulations.gov API Guide. The Federal Register API guide covers the published rules themselves.
• Amendment History and Point-in-Time Law explains what a legal data service can and cannot tell you about what a rule said on an earlier date.
• How to Know When a State Law Has Changed teaches you to read history lines, effective dates and status words.
• Regulatory Monitoring covers how to keep track of rule changes, and Regulatory Mapping shows how to connect each rule to a duty in your business.

If you are comparing vendors' APIs

Buyers often start from a vendor's name. These guides read each company's own pages and say what is documented, who can use it and what to ask.

• Westlaw API: What Exists, Who Can Use It and What It Covers covers Thomson Reuters's developer portal and its terms.
• LexisNexis API: What the Developer Portal Offers separates the legal content APIs from the rest of the catalog.
• Lexis+ AI, CoCounsel and Westlaw AI: Is There an API? answers the question for each AI assistant.
• LexisNexis and Westlaw API Alternatives for Developers is a decision path for engineers who cannot get a contract API.
• Fastcase, vLex and Clio: Which APIs Exist? and the Clio API guide cover the practice-management side.
• Midpage API: What It Offers and Who It Fits and Do Harvey and Legora Have APIs? cover the newer vendors.

For engineers

These guides include code, but each opens with a plain-English summary, so you can forward one to a colleague who does not read code.

• USLM vs Akoma Ntoso: How to Read Legislative XML covers the two XML formats (structured text that software can read) used for legislation. USLM is the one the US government publishes the Code in, and Akoma Ntoso is an international standard it relates to.
• US Statutes API: The Guide to USC, CFR, and State Code Access compares the main ways to get the US Code and state codes.
• CFR API, State Regulations API and State Court Rules API cover federal regulations, state regulations and court rules.
• Statutes at Large API covers federal law as it was enacted.
• Compliance API: Two Meanings, and Where Regulatory Data Comes From clears up a term that means two different things.
• Legal Web Scraping: What Breaks on State Legislature Sites is a field guide to the problems of collecting state law yourself.

Quick finder

FAQ

What is US law data? It is the text of US law in a searchable, storable form. That includes statutes, regulations, court rules, agency guidance, attorney general opinions and court decisions. Governments publish most of it, but not in one place or one format.

Is US law data free? Much of the law itself is free to read on government sites. What costs money is cleaning, combining and keeping it current across many publishers, plus commentary and some court records. The legal data buyer's guide explains what drives the price.

How do I know a copy of a law is official? Check who published it and whether that publisher says its copy is the official one. Some well-known free sites say plainly that they are not the legal record. The provenance guide shows how to check.

What is the difference between a bill, a session law and a statute? A bill is a proposal. A session law is the law as passed. A statute, in the code, is the organized version after the law is merged in. The session law guide explains the difference.

Where can I get US law data for my own software? You can collect it from each publisher, license it from a supplier, or combine both. Vaquill AI offers a legal data API covering US statutes, regulations and related primary law. The vendor questions work for any supplier, including us.

Is this legal advice? No. These guides explain what the law says and where to find it. Whether a law applies to you is a question for a lawyer.

If you need statute and regulation text for your own product, see the US primary law API and check it against the ten vendor questions above.

Priyansh Khodiyar

Co-Founder & CTO

Priyansh leads engineering and AI at Vaquill AI: the pipelines that pull statutes, regulations and court rules from every US jurisdiction's official publisher, and the REST API, MCP server and open dataset that serve them.