Rules of Decisions Act (28 USC 1652):
"States laws as rules of decisions:
The laws of several states, except where the Constitution or treaties of
Rules Enabling Act (28 USC 2071):
These acts enable courts established by act of Congress to prescribe rules for the conduct of their business, as long as these rules are consistent with US Supreme Court rules of practice and procedure and acts of Congress, as well as outline the procedure for rule prescription, scope of the rules, and publication of the rules.
US Code: Judiciary and Judicial Procedure: