The Festo litigation has probably come to an end, Findlaw reports. After 17 years and two trips to the Supreme Court, the Massachusetts District Court has dismissed Festo’s case. Festo sued SMC and Shoketsu Kinzoku Kogyo Kabushiki Co. Ltd based on Festo’s patent for two patents relating to magnetically coupled rodless cylinders. In the course of the proceedings, Festo amended its patent to make it clear that the inventions contain a pair of sealing rings and that the outer shell of the device, called the sleeve, were magnetizable. SMC and Shoketsu Kinzoku Kogyo Kabushiki Co. Ltd claimed that, following the amendment, its device fell outside the terms of the patent since it had only one sealing ring and was non-magnetizable. This argument caused the first visit to the Supreme Court to clarify the doctrine of equivalents. This doctrine prevents defendants from making insubstantial changes that allow it to escape the literal scope of the patent. The second visit was based on prosecution history estoppel – this doctrine prevents a patentee from amending its patent in order to obtain the patent and then using the elements of the patent that it had to give up during the amendment against the defendant.
Prosecution history estoppel eventually killed Festo’s case according to the judge in the District Court:
"Because both the single sealing ring and non-magnetizable sleeve were foreseeable to a person of ordinary skill in the art at the time of the 1981 amendments, Festo is unable to rebut the presumption of surrender of these two elements."If Festo wanted to keep hold of the equivalents, it should have said so. It is still open to Festo to appeal.
The IPKat points out that the UK has had its own version of Festo in the Kirin-Amgen litigation.
Other things that happen in 17 years here, here and here