About FMCSR.com

What is covered

49 CFR Part 40 (DOT workplace drug and alcohol testing procedures) and all of Chapter III, Parts 300 through 399, the Federal Motor Carrier Safety Administration's regulations. That is the same scope as the printed Green Book. Parts that no longer exist (355, 356, 388) are kept for historical lookups. The Hazardous Materials Regulations in Parts 100–185 are not included.

Today: 1,304 sections across 39 parts, current through October 15, 2026. Including history: 4,758 distinct wordings back to October 1, 1996.

Where the text comes from

Nothing here is paraphrased or retyped. Every word is parsed from the government's own machine-readable publications:

• 2017 to today: the eCFR(ecfr.gov), the Office of the Federal Register's daily-updated codification. Its point-in-time API gives the text of each section on any date from January 1, 2017 forward, so changes are recorded to the day they took effect.
• 1996 to 2016: annual CFR editions from govinfo.gov (Government Publishing Office). Title 49 is revised as of October 1 each year, so before 2017 the record is one snapshot per year. govinfo does not publish the 1997 edition of Parts 300–399 in XML, so the 1996 text stands in for that year.

The site checks the eCFR for new amendments every day and rebuilds itself when anything changes. The "current through" date in the footer is the eCFR's own currency date.

How the as-of date works

Set a date in the header (or on the home page) and it travels with you: browse, search, every section page and the AI assistant all switch to the wording in force on that date. Sections that did not exist yet, or had been removed, drop out of the lists.

A section's history is built by comparing the regulatory words between consecutive government snapshots. Each time the words change, a new entry starts. Differences that are only typography (quote marks, dashes, spacing) or editorial apparatus (effective date notes) do not create entries. The bracketed Federal Register citations printed with each section are the authoritative amendment history and are shown alongside every version.

Precision. From Jan. 1, 2017 onward, dates are exact. Before that, a wording is dated to the annual edition that first printed it, which means an amendment effective in, say, March 2010 appears with the October 1, 2010 edition. When you read a pre-2017 date the page says so and points you to the citations for the exact effective date.

Redesignations. A few appendices moved. The Minimum Periodic Inspection Standards, for example, were Appendix G to Subchapter B until October 2021 and are Appendix A to Part 396 today; the site shows them under one address with the earlier designation noted.

Search

Full-text search over every section, ranked by relevance, with prefix matching so "disqualif" finds every form of the word. With a case date set, search runs over the historical wordings in force on that date. Typing a citation such as 395.3 or 49 CFR 391.41 opens the section directly.

Ask AI

The assistant runs on Claude (Anthropic). For each question it searches the regulations as of your chosen date, hands the model only the relevant section text, and instructs it to answer from that text alone and cite every statement to a section and paragraph. Links on the citations open the exact wording it read. It does not have FMCSA guidance, regulatory interpretations, state law or case law, and it is told to say so rather than guess.

Treat it the way you would treat a sharp research assistant: fast at finding the right place, not a substitute for reading it. Usage is rate-limited per visitor so the tool can stay free.

Citing and exhibits

Every section page has copy buttons for a Bluebook-style citation and a permanent link that carries the as-of date, plus a Print / PDF view that stamps the section with its effective range, source and retrieval date. Each version also links to its official government source (the eCFR page for that date, or the govinfo record for that annual edition) so the text can be verified independently.

Limits and disclaimer

FMCSR.com is an unofficial compilation. It is not affiliated with FMCSA, the Office of the Federal Register or the Government Publishing Office. Parsing government XML is not perfect; tables and figures in particular may render imperfectly, and figures are omitted with a note. Always verify against the official source before relying on a provision in a filing, and check the Federal Register for amendments with delayed or staggered effective dates. Nothing on this site is legal advice.

Who built it

Lars Daniel, Director of Digital Forensics and AI, Rimkus, court-qualified digital forensics expert, Forbes contributor and author of The Trucking Defense Guide to Cell Phone Forensics. He built the first version so he could stop carrying the Green Book to depositions; the as-of-date history came from the same cases, where the question is never "what does the rule say" but "what did it say that day."

Have a case? Lars consults and testifies on digital evidence in trucking litigation: cell phone forensics, ELD and telematics data, and the FMCSR questions that come with them. lars.daniel@rimkus.com.

Questions, corrections and feature requests about the site: lars@thelarsdaniel.com. The site is free and ad-free.