FindLaw is a searchable database of U.S. Supreme Court decisions since 1760. Supreme Court opinions are browsable by year and U.S. Reports volume number, and are searchable by party name, case title, citation, full text and docket number. FindLaw maintains an archive of Supreme Court opinion summaries from September 2000 to the present. Summarized cases are browsable by date and searchable by docket number, case title, and full text.

GovInfo provides public access to official publications from all three branches of the Federal Government.

Includes an extensive database of federal cases.

From Cornell Law School, LII provides open access to legal materials, including: annotated version of the constitution, federal statutes, Supreme Court decisions, CFR, and more.

Oyez is a free law project from Cornell’s Legal Information Institute (LII), Justia, and Chicago-Kent College of Law—is a multimedia archive devoted to making the Supreme Court of the United States accessible to everyone....Oyez offers transcript-synchronized and searchable audio, plain-English case summaries, illustrated decision information, and full-text Supreme Court opinions (through Justia).
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The United States Code is a consolidation and codification by subject matter of the general and permanent laws of the United States. It is prepared by the Office of the Law Revision Counsel of the United States House of Representatives.

This site includes full text of certain materials, including many opinions. It also suggests resources for finding briefs.