The Federal Rules of Civil Procedure (officially abbreviated Fed. R. Civ. P.; colloquially FRCP) govern civil procedure (i.e. for civil lawsuits) in United States district (federal) courts. The FRCP are promulgated by the United States Supreme Court pursuant to the Rules Enabling Act, and then the United States Congress has seven months to veto the rules promulgated or they become part of the FRCP. The Court's modifications to the rules are usually based upon recommendations from the Judicial Conference of the United States, the federal judiciary's internal policy-making body. Although federal courts are required to apply the substantive law of the states as rules of decision in cases where state law is in question, the federal courts almost always use the FRCP as their rules of procedure. (States may determine their own rules, which apply in state courts, although most states have adopted rules that are based on the FRCP.)
The Rules, established in 1938, replaced the earlier procedures under the Federal Equity Rules and the Conformity Act (28 USC 724 (1934)) merging the procedure for cases, in law and equity. The Conformity Act required that procedures in suits at law conform to state practice usually the Field Code and common law pleading systems. Significant revisions have been made to the FRCP in 1948, 1963, 1966, 1970, 1980, 1983, 1987, 1993, 2000, and 2006. (The FRCP contains a notes section that details the changes of each revision since 1938, explaining the rationale behind the language). The revisions that took effect in December 2006 made practical changes to discovery rules to make it easier for courts and litigating parties to manage electronic records.
The Federal Rules of Civil Procedure were amended in 1966 to unify the civil and admiralty procedure, and added the Supplemental Rules for Certain Admiralty and Maritime Claims (now Supplemental Rules for Admiralty or Maritime Claims and Asset Forfeiture Actions).