USC vs. CFR: Statutes, Regulations, and Judicial Review

The United States Code and the Code of Federal Regulations are the two main collections of federal law, and the difference between them comes down to who writes what. The USC holds the statutes Congress passes. The CFR holds the rules federal agencies write to put those statutes into practice. In any comparison of the USC vs. the CFR, that authorship gap explains almost everything else: the hierarchy between them, how they get updated, how they’re challenged in court, and which one you need to open first when researching a federal legal question.

What the United States Code Contains

The United States Code is the organized collection of the country’s general and permanent federal laws, arranged into 54 subject-matter titles.¹ Everything in it started as a bill. The House and Senate pass it, the President signs it (or Congress overrides a veto), and the new law is placed into the title that already covers its subject. Title 18 covers crimes and criminal procedure. Title 26 is the tax code. Title 42 covers public health and welfare.

A citation like 18 U.S.C. § 1001 points to one such statute: the federal false statements law, which makes it a crime to knowingly lie to a government agency and sets a penalty of up to five years in prison.² The statute defines the offense and the penalty. It does not tell each agency how to investigate or document violations. That level of detail lives somewhere else.

What the Code of Federal Regulations Contains

The Code of Federal Regulations is the codified collection of rules written by federal executive agencies.³ The EPA, the FDA, the SEC, OSHA, and every other federal regulator publishes its rules here. Where a statute might say “the agency shall establish safety standards for workplace machinery,” the CFR regulation gives the actual guardrail heights, inspection intervals, and reporting forms.

The CFR is divided into 50 titles by broad regulatory subject. Each title is broken into chapters (usually named for the issuing agency), and chapters break down further into parts and sections.³ A citation like 21 C.F.R. § 100.1 tells you Title 21 (Food and Drugs), Part 100, Section 1.⁴

One boundary worth naming: the CFR contains only final, binding regulatory text. Proposed rules, agency notices, policy statements, and executive orders live in the Federal Register, not the CFR.

Statutes Sit Above Regulations

The USC and the CFR are not equals. Statutes occupy the higher rung, and regulations must stay within the space statutes create. The link between them is what’s often called enabling legislation: Congress passes a statute that gives a particular agency the power to write rules on a defined subject. Without that statutory grant, the agency has no authority to regulate at all.

The enabling statute sets a ceiling. An agency can fill in details underneath, but it cannot go past the authority Congress handed it. If an agency’s statute lets it regulate air pollutants from power plants, the agency cannot use the same authority to regulate water discharges from farms.

When someone challenges a regulation in court, the central question is usually whether the agency stayed in that lane. Under the Administrative Procedure Act, a reviewing court must set aside any agency action that exceeds statutory authority or is otherwise not in accordance with law.⁵ A regulation that contradicts or overshoots its statute can be struck down.

How a Regulation Gets Into the CFR

An agency cannot draft a rule and impose it. The Administrative Procedure Act sets out a public process, usually called notice-and-comment rulemaking.⁶

The agency publishes a Notice of Proposed Rulemaking in the Federal Register, describing the legal authority for the rule and either the proposed text or a summary of the issues.
The agency opens a comment period, typically 30 to 60 days, during which anyone can submit written feedback. More complex rulemakings sometimes run 180 days or longer.⁷
After reviewing comments, the agency publishes a final rule in the Federal Register with a statement of its basis and purpose. The rule generally cannot take effect until at least 30 days after publication.⁶
Once the rule is effective, it is incorporated into the appropriate title, chapter, and part of the CFR.

Some categories skip parts of this process. Interpretive rules, general policy statements, and situations where the agency finds good cause that normal procedures are impractical can move outside notice-and-comment.⁶ For substantive regulations that create enforceable obligations, though, the public process is required.

The Federal Register vs. the CFR

The Federal Register is the government’s daily journal of agency actions, published by the Office of the Federal Register at the National Archives. It carries proposed rules, final rules, agency notices, and presidential documents such as executive orders.⁸ The CFR is where finalized rules end up once they leave that daily stream and become codified regulatory text.

So the sequence for any regulation runs: proposal in the Federal Register, comment period, final rule in the Federal Register, then codification into the CFR after the rule takes effect.

How Each One Is Updated

The USC is updated on a rolling basis as Congress passes new laws. When a statute is enacted, its provisions are placed into the relevant title.

The printed CFR works differently. It follows a staggered annual publication schedule: Titles 1–16 are 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 1.⁹ Between annual editions, new final rules go into the Federal Register and are incorporated into the unofficial electronic CFR (eCFR) on a daily basis.¹⁰ For any fast-moving regulatory area, the eCFR is more current than the last printed edition.

How Courts Review Regulations Now

Regulations carry the force of law, but they are not immune from challenge. The APA gives courts broad power to review agency action and strike down rules that are arbitrary, exceed statutory authority, or violate the Constitution.⁵ Two recent developments have changed how that review plays out.

The End of Chevron Deference

For four decades, courts followed a framework called Chevron deference: when a statute was ambiguous, judges deferred to the agency’s interpretation as long as it was reasonable. In June 2024, the Supreme Court overruled that framework in Loper Bright Enterprises v. Raimondo. The Court held that the APA requires judges to exercise their own independent judgment about what a statute means, even when the statute is unclear.¹¹ Courts can still treat an agency’s reasoning as useful, but they no longer have to accept it just because reasonable minds could differ about the statute’s meaning.

The practical result is that regulations which used to survive because they fell inside a zone of reasonable interpretation now face harder review. If the court reads the statute differently than the agency did, the regulation can fall.

The Major Questions Doctrine

The Supreme Court has also signaled through several recent cases that when an agency claims authority over an issue of vast economic or political significance, courts will not accept the claim unless Congress spoke clearly in the statute. An ambiguous or general grant of power is not enough to support a regulation with sweeping national consequences. The idea is that Congress does not delegate decisions of that magnitude through vague language.

Reading a USC or CFR Citation

Legal citations follow a simple structure once you see the pattern.

A USC citation like 18 U.S.C. § 1001 reads as Title 18 (Crimes and Criminal Procedure), United States Code, Section 1001. The section is the basic unit of every Code title.¹

A CFR citation like 21 C.F.R. § 100.1 reads as Title 21 (Food and Drugs), Code of Federal Regulations, Part 100, Section 1. The number before the decimal is the part; the number after it is the section within that part.⁴

Seeing “U.S.C.” tells you the source is a statute in the United States Code. Seeing “C.F.R.” tells you the source is a regulation in the Code of Federal Regulations. The title number narrows the subject; the section number pinpoints the provision.

Where to Read the USC and CFR Online

Both codes are free online through official government websites.

For the United States Code, the most authoritative source is the Office of the Law Revision Counsel at uscode.house.gov, which maintains the current official version.¹ Cornell Law’s Legal Information Institute at law.cornell.edu mirrors the Code and adds annotations.

For the CFR, there are two primary options. GovInfo (govinfo.gov) hosts the official annual edition, which matches the printed version.¹⁰ The eCFR at ecfr.gov is an unofficial version that folds in Federal Register amendments daily, so it is more current than the annual edition but is not the official legal text.¹² For most research the eCFR is the better starting point; for anything you plan to rely on in a legal proceeding, confirm the text against the official edition on GovInfo.

The Federal Register itself is at federalregister.gov and on GovInfo, and Regulations.gov is the portal for submitting public comments on proposed rules. Together those sites give you the full picture: the statutes in the USC, the regulations in the CFR, and the daily flow of proposals and final rules that moves material between them.

1
Office of the Law Revision Counsel. Detailed Guide to the United States Code Content and Features
2
Office of the Law Revision Counsel. 18 USC 1001 – Statements or Entries Generally
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eCFR. Titles
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eCFR. 1 CFR 8.9 – Form of Citation
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Office of the Law Revision Counsel. 5 USC 706 – Scope of Review
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Office of the Law Revision Counsel. 5 USC 553 – Rule Making
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Office of the Federal Register. The Rulemaking Process
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GovInfo. Federal Register
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U.S. Government Publishing Office. When Will the Code of Federal Regulations (CFR) Be Published on GovInfo
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GovInfo. Code of Federal Regulations (CFR)
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Supreme Court of the United States. Loper Bright Enterprises v. Raimondo
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eCFR. 3 CFR Chapter I – Executive Office of the President