How to Read a Regulation

Three different documents get called "the regulation," and they carry different weight. The regulatory text is the codified language that appears in the Code of Federal Regulations. It is the only part that has the force of law. The preamble is the explanatory material an agency publishes in the Federal Register alongside a proposed or final rule — the statement of basis and purpose required by 5 U.S.C. § 553(c), plus the agency's responses to comments. Guidance documents (manuals, FAQs, advisory opinions, interpretive memos) sit outside both and generally bind nobody.

When someone hands you a PDF from an agency website, ask which of the three it is. A Federal Register final rule contains both preamble and regulatory text, but only the block at the end labeled with amendatory instructions ("Revise § 122.21 to read as follows") becomes law. Interpretive rules and policy statements are exempt from notice and comment under § 553(b)(A), and Perez v. Mortgage Bankers Ass'n confirmed that an agency may amend or repeal them without notice and comment. That procedural shortcut is a signal about how much force the document has.

The CFR has 50 titles, roughly parallel to but not identical with the U.S. Code titles. Title 29 is Labor. Within a title, material is organized into chapters (usually one per agency — Chapter XVII is OSHA), then subchapters, then parts, then subparts, then sections. The number before the period in a section is the part; the number after is the section. So § 1910.132 is Part 1910, section 132. Parts matter because definitions, scope, and applicability provisions are usually set at the part or subpart level, not repeated in each section.

Below the section, agencies follow a fixed drafting hierarchy: (a), then (1), then (i), then (A), then (1), then (i) again in italics. If you are quoting a requirement, cite to the deepest unit that actually contains the obligation. Courts and opposing counsel will hold you to the exact paragraph, because a condition in (d)(1)(i) may be qualified by an exemption three paragraphs down in (d)(3).

Two structural quirks trip students up. "[Reserved]" means the agency deliberately left a slot empty — do not assume the material was repealed. And appendices to a part may be either mandatory or explanatory; the appendix's own heading or the part's text tells you which.

Do not start at the section you were sent to. Start at the beginning of the part and read four things in order: the purpose/scope section, the applicability section, the definitions section, and any exemptions. Regulatory definitions routinely override ordinary meaning — an agency can define "employer," "discharge," or "solid waste" in ways that decide your case before you reach the operative provision. Check whether the definition is stated as applying to the part, the subpart, or only "as used in this section."

Then read the operative section for the actor, the trigger, the obligation, and the timing. Ask: who must act, on what condition, by when, and what happens if they do not. Distinguish mandatory language ("must," "shall") from discretionary ("may") and from aspirational ("should"). Modern federal drafting prefers "must" for obligations, so a stray "should" in a recently amended rule is often deliberate.

Finally, chase the cross-references. Regulations are dense with internal citations and with incorporation by reference of outside standards (ANSI, ASTM, NFPA) under 1 C.F.R. part 51. If a rule incorporates a private standard, that standard's text is legally binding even though it is not printed in the CFR.

Because the preamble is where the agency explains the ambiguity you are litigating. If the text is unclear, the response-to-comments section usually addresses the exact question — often because a commenter raised it. Preambles also supply the agency's reasoning, which is what a court reviews for arbitrariness under 5 U.S.C. § 706(2)(A) and Motor Vehicle Manufacturers Ass'n v. State Farm Mutual Automobile Insurance Co., 463 U.S. 29 (1983). A rule that changes course without acknowledging the change is vulnerable, and the preamble is where you find out whether the agency acknowledged it.

You find the preamble through the source note printed at the end of each CFR section or at the head of the part. It reads like "Source: 87 FR 12345, Mar. 3, 2022, unless otherwise noted," with later amendments listed after the section text. Each of those Federal Register citations takes you to the document that created or changed the language. Trace the specific paragraph you care about back to the specific rulemaking that added it — not just the original 1978 promulgation.

Use the eCFR (ecfr.gov), which is updated continuously and shows an "updated as of" date. The bound annual CFR is a snapshot: titles 1–16 revised as of January 1, titles 17–27 as of April 1, titles 28–41 as of July 1, and titles 42–50 as of October 1. If you need the text as of a past date, the eCFR's point-in-time feature and the annual editions on GovInfo are your tools. For amendments published but not yet incorporated, check the List of CFR Sections Affected (LSA) and the current Federal Register issues.

Then read the authority note at the top of the part. It lists the statutes the agency claims as authority — for example, "Authority: 42 U.S.C. 7401 et seq." Pull those statutes. After Loper Bright Enterprises v. Raimondo (2024) overruled Chevron, courts exercise independent judgment on whether a statute authorizes the rule; the agency's reading no longer gets controlling deference merely because the statute is ambiguous, though Skidmore v. Swift & Co., 323 U.S. 134 (1944), still gives well-reasoned agency views persuasive weight, and express delegations of discretion are respected within their bounds. When the fight is over what the agency's own regulation means rather than what the statute means, Kisor v. Wilkie (2019) sharply narrowed Auer deference: the rule must be genuinely ambiguous after exhausting the standard tools, and the agency's reading must be authoritative, implicate its expertise, and reflect fair and considered judgment.

Finally, check whether the rule is still on the books in practice. A regulation can be vacated by a court, withdrawn, stayed pending review, or disapproved by Congress under the Congressional Review Act, 5 U.S.C. §§ 801–808, and the CFR text may lag. Run the citation through a citator and search recent Federal Register documents for the part number.

Codified federal regulations use Bluebook Rule 14.2: 40 C.F.R. § 122.21 (2023), with the year of the CFR edition you consulted. Cite by section, and use "pt." for a whole part. Uncodified or newly published material is cited to the Federal Register: 88 Fed. Reg. 12,345 (Feb. 27, 2023) (to be codified at 40 C.F.R. pt. 122). Note the comma in the page number and the required parenthetical identifying where it will land in the CFR. For a proposed rule, add "(proposed Feb. 27, 2023)" and identify it as such.

State regulations vary enormously in structure and naming — California Code of Regulations, New York Codes, Rules and Regulations, Texas Administrative Code — and each has its own citation form in Bluebook Table T1.3. Some states publish a register comparable to the Federal Register; others have thin or delayed publication, which makes currency checking harder. Some states also have their own APAs that differ from the federal model on rulemaking procedure and deference, so do not assume federal doctrine transfers.