American Jurisprudence (second edition is cited as Am. Jur. 2d) is a legal encyclopedia of the United States law, published by West. It was originated by Lawyers Cooperative Publishing, which was subsequently acquired by the Thomson Corporation. The series is now in its second edition, launched in 1962. It is a staple of law libraries, and the current edition is over 140 volumes, updated with replacement volumes, annual pocket supplements, and a New Topic Service binder. The discussion has extensive research references to other Thomson West publications, including sister publications Am. Jur. Trials, Am. Jur. Proof of Facts, Am. Jur. Pleading and Practice Forms, and Am. Jur. Legal Forms. Before Thomson's acquisition of West Publishing, it was a competitor to Corpus Juris Secundum. Am. Jur. is available online through both  Westlaw, and LexisNexis.

The law of the United States comprises many levels of codified and uncodified forms of law, of which the most important is the United States Constitution, the foundation of the federal government of the United States. The Constitution sets out the boundaries of federal law, which consists of acts of Congress, treaties ratified by the Senate, regulations promulgated by the executive branch, and case law originating from the federal judiciary. The United States Code is the official compilation and codification of general and permanent federal statutory law.