Congress is unable to make any law or provision therein to reopen cases which have been previously adjudicated by or within federal courts. Congress violates the separation of powers principle when it orders federal courts to reopen their final judgments. Decided April 18, 1995 (argued November 30, 1994). Opinion of the Court: Antonin Scalia → go there Dissenting: Stevens. Topic: Separation of powers. Plaut v. Spendthrift Farm, Inc., 514 U.S. 211 (1995), was a landmark case about separation of powers in which the Supreme Court of the United States held that Congress may not retroactively require federal courts to reopen final judgments. Writing for the Court, Justice Scalia asserted that such action amounted to an unauthorized encroachment by Congress upon the powers of the judiciary and, therefore, violated the separation of powers as a constitutional concept. Wiki link