Vas-Cath Inc. v. Mahurkar

Vas-Cath (plaintiff) sought declaratory judgment of non-infringement and invalidity against two of Mahurkar's (defendant) catheter patents, and Mahurkar counterclaimed infringement. Mahurkar had filed a U.S. design patent application in March 1982 that he later abandoned in November 1984, but before abandonment, filed an identical-figure Canadian design application that issued as a patent that August. Mahurkar's later U.S. utility patent applications, filed in October 1984 and January 1986, used the same figures as the abandoned design application and claimed priority back to it; the patent office found these utility claims fully supported by the abandoned design application's disclosure, and they issued as the '329 and '141 patents. At trial, Vas-Cath argued the design application didn't sufficiently support the utility claims to justify that earlier priority date — meaning if the utility patents couldn't rely on the design application's filing date, the Canadian design patent would become invalidating prior art against them. The district court agreed with Vas-Cath and held the utility patents anticipated; Mahurkar appealed.