A federal statute is a written law passed by the legislature and signed into law by the executive (President).
The statute is published initially as a slip law. Each slip law is published individually and assigned a number. All slip laws for a particular legislative session are then compiled into a set of "session laws."
Federal session laws are compiled, in chronological order in the "Statutes at Large." U.S. Statutes at Large is the official source, published by the GPO, for the laws and resolutions passed by Congress. The Statutes at Large is also available online through HeinOnline and ProQuest Congressional. The Library of Congress also offers free access to session laws, from 1973 to the present, through Thomas: Legislative Information on the Internet. United States Code Congressional & Administrative News ("U.S.C.C.A.N.") is an unofficial source of federal session laws published by West.
The statute is then incorporated into the Statutory Code - a compilation of all statutes in force for the jurisdiction - by subject matter.
The United States Code (U.S.C.) is the official source of the Federal Code. It is published by the Office of the Law Revision Counsel of the U.S. House of Representatives. It is published every six years and updated in the interim with annual bound cumulative supplements. It is also available online through the US GPO. There are also two unofficial versions of the Code - The United States Code Annotated ("U.S.C.A.") (also available on Westlaw) and United States Code Service ("U.S.C.S.") (also available on Lexis) - which are updated more frequently than the official Code. These unofficial codes are annotated with digests of cases that have interpreted statutory provisions, and also include helpful tables and indexes.
For a more indepth look at statutory research, see the Statutes and Constitutions Research Guide
As with case law, the best place to start when doing statutory research is by using secondary source materials. Secondary sources such as legal treatises, encyclopedia, and law review articles will often refer to the controlling statutes in an area of law and are good starting places for statutory research.
There are 51 Titles in the U.S. Code. Code titles are divided into chapters, which are further divided into sections. Only the title and section numbers are used to cite to particular code sections. For example, if you were looking for the statute that prohibits debt collectors from harassing consumers: Title 15 covers "Commerce and Trade" but is subdivided into 110 chapters; chapter 41 covers "Consumer Credit Protection" and is subdivided into 6 subchapters; subchapter V covers "Debt Collection Practices" and consists of sections 1692 - 1692p; section 1692d covers harassment and abuse, so the citation would be 15 U.S.C. § 1692d.
By Citation: If you already have a citation to a federal statute code section, you can go right to the text of that section in one of the print versions of the code. The spine of each volume of the code will tell you what title(s) and section range(s) are included in that volume. Once you read your code section in the bound volume, check the pocket part or supplement for that volume to see if the code section has been amended. You may also find the code sections using Westlaw, Lexis or one of the free sites such as the GPO Access website or the Cornell University Law School, Legal Information Institute's U.S. Code Collection page (see below)
By Popular Name: The print versions of the U.S. Code contain a "Popular Name" table at the end of the General Index if you do not know the citation (e.g. USA Patriot Act, Civil Rights Act). There are also several online versions of the Popular Name index on the free sites such as the Cornell University Law School, Legal Information Institute's Table of Popular Names page, the U.S. House of Representatives Office of the Law Revision Counsel page. You may also find statutes by Popular Name on Westlaw and Lexis.
By Topic: If you do not have a citation or name of a statute, and you didn't find what you were looking for using the secondary source materials, the Federal Code also includes a subject index at the end of each set. Both Cornell University Law School's Legal Information Institute's U.S.Code Collection as well as the U.S. House of Representatives' Search the United States Code database allow you to conduct a key word search of the federal code to find relevant code sections. Keyword searching is also available on Westlaw and Lexis. USCCAN and Statutes at Large also contain subject indexes for each legislative session.
By Public Law Cite: Parallel Reference Tables, located in the Tables volumes of U.S.C., U.S.C.A. and U.S.C.S. can be used to convert Public Law numbers and Statutes at Large cites to U.S.C. cites. There are also tables in Statutes at Large and USCCAN to convert bill numbers to Public Law numbers.
As with case law, statutes are constantly evolving. Before relying on a statute as authority, you must verify that it has not been amended or repealed.
Start by checking the annual pocket parts and updated supplements. The unoffical versions of the Code (U.S.C.A. and U.S.C.S.) are generally updated monthly. However, the print versions supplements are often issued too slowly to provide thorough updating, so it may be best in this case to use online sources.
All online versions of the U.S. Code are regularly updated to include recent session laws too new to be incorporated in print version updates. This information generally accompanies each section of the Code.
On Westlaw, use KeyCite to identify pending legislation that may affect the statute.
On Lexis, use Shepards to identify pending legislation that may affect the statute.
Proposed legislation - For the current Congress, separate bill summary & status and bill text databases on Congress.gov can be keyword (or index) searched by date for proposed additions or amendments to the U.S. Code. Congressional bills are also keyword searchable on GPOAccess.
Judicial history: To establish the current validity of an existing statute the caselaw of the courts of the jurisdiction in which it governs should also be searched for supreme court constitutionality rulings and other holdings affecting its "good law" status. LexisNexis Shepard's and KeyCite on Westlaw, in addition to tracing legislative changes, also assist in determining the judicial history of statutory provisions.