Rules of Decision Act
From Wikipedia, the free encyclopedia
The Rules of Decision Act requires that federal courts apply state law in their decisions, except when in conflict with federal law.
This act came from Section 34 of the Judiciary Act of 1789. It is now codified, in slightly different form, in 28 U.S.C. ยง 1652.
Its interpretation was central to the issue in Erie Railroad Co. v. Tompkins.