Federal Law

U.S. Code

At U.S. House of Representatives Internet Law Library, search the entire United States Code

Code of Federal Regulations

At National Archieves, search the entire Code of Federal Regulations

United States Supreme Court

Find Law, keeps all U.S. Supreme Court cases since 1893.

At The Oyez Project, listen to recordings of oral arguments before the United States Supreme Court in historically cases. This site is rich with other U.S. Supreme Court information as well.

Federal District and Circuit Courts

Federal Court filings are generally available from PACER. PACER is a fee based system which requires registration for a password. More information is available at the PACER service center.
Each court participating in PACER will have its own login address. Additionally, there is a national Party/Case Index.

Find Law has links to all Federal Circuit Courts of Appeal.

Find Law has links to Federal District Courts.

At Justia.com you will find US Court of Appeals Cases and Opinions.

Federal Court Rules

The Legal Information Institute at Cornell provides:
The Federal Rules of Civil Procedure
The Federal Rules of Evidence
The Rules of the U.S. Supreme Court

Federal Agencies and Departments

USA.gov is the official comprehensive government index.

At Tax Sites, a comprehensive index of tax and accounting resources.