United States v. Carlton, 512 U.S. 26 (1994)

 
The earlier cases are listed here:
But "the Court has never intimated that Congress possesses unlimited power to 'readjust rights and burdens ... and upset otherwise settled expectations.''' Connolly v. Pension Benefit Guaranty Corporation, 475 U. S. 211, 229 (1986) (O'CONNOR, J., concurring) (brackets omitted), quoting Usery v. Turner Elkhorn Mining Co., 428 U. S. 1, 16 (1976).