Thomas and Betts Co. (P) sued Electrical Fittings Corp. (D) in equity for a patent infringement. The district court held Claim 1 to be valid and then dismissed the suit for failure to prove infringement. P did not appeal. P filed a disclaimer of Claim 2 with the Patent Office. D appealed the part of the decree that adjudicated Claim 1 valid. The circuit court of appeals dismissed the appeal; D had been awarded all the relief to which it was entitled. The Supreme Court granted certiorari.