Fresenius Medical Care and Baxter International have been involved in a series of infringement disputes over the last decade concerning the features of dialysis machines produced by each company. Litigation between the two sides may be nearing its end after a unique application of the USPTO's post-grant review process.

Fresenius originally sought declaratory judgments of invalidity on several Baxter patents. A District Court eventually upheld the validity of Baxter's claims relating to touch-screen functionality, leading Baxter to respond with an infringement countersuit that yielded approximately $14 million in damages. However, amid this prolonged litigation Fresenius also requested a post-grant administrative proceeding which ultimately saw USPTO examiners contradict the District Court verdict and judge Baxter's inventions obvious and patents void.

This month, the USPTO's cancelation of Baxter's asserted patent claims was applied in parallel proceedings in the U.S. Court of Appeals where Fresenius has successfully seen outstanding infringement claims against it dismissed.

As PatentlyO's Dennis Crouch noted, it is not uncommon for disputed patents to be involved in parallel proceedings such as a civil suit and as USPTO reexamination. However, there has been somewhat of a legal gray area for how to proceed when two different jurisdictions disagree on the validity of a patent. In this case, the fact that the appellate court ruled that the USPTO findings trumped prior District Court rulings could set an important precedent.