Kaiser Industries Corp. v. Jones & Laughlin Steel Corp‪.‬

Opinion OF THE COURT ADAMS, Circuit Judge, Before the landmark case of Blonder-Tongue Laboratories, Inc. v. University of Illinois Foundation1 was catapulted onto the legal horizon, the rule was that no general collateral estoppel effect attached to a judicial determination of patent invalidity. In Blonder-Tongue, the Supreme Court held that a prior adjudication of invalidity may be asserted as a defense to a subsequent attempt to enforce the patent, and that such defense must be accepted unless it is demonstrated that the patentee was denied a full and fair opportunity to litigate in the earlier action. The plaintiffs here sought to enforce a patent that had been held invalid in a previous suit.2 The defendant asserted the defense of collateral estoppel, but the district court refused to accept it.3 Since in the first suit the patentees were afforded a full and fair opportunity to litigate that satisfied the criteria established in Blonder-Tongue, we hold that the district court was obliged to accept the defense of collateral estoppel.