Parklane Hosiery Co. v. Shore

In Blonder-Tongue Labs., Inc. v. University of Ill. Foundation, 402 U.S. 313 (1971), the US Supreme Court allowed the use of Defensive Non-Mutual Issue Preclusion in federal court in the context of a patent claim. The patentee in that case had earlier brought a patent claim but the court in the first case found the patent invalid. In Blonder-Tongue, the Court held that in future actions asserting the same patent the defendants could assert defensively the earlier holding that the patent was not valid.

That set the stage for the case that follows, which addresses Offensive Non-Mutual Issue Preclusion.