Sonos v. Google: The Return Of Prosecution Laches?

In a recent decision (the Sonos case), the U.S. District Court for the Northern District of California has potentially breathed new life into a dormant doctrine—the doctrine of prosecution laches.¹

While this doctrine has existed for years, it has rarely been applied, except for its repeated use against the Lemelson Foundation² and Gilbert Hyatt.³ However, those cases relate to a narrow (albeit numerous) group of patent applications with priority dates claiming the benefit of patents filed before the pre-1995 change in patent law but issued after 1995 – so-called "submarine patents." This is a significant distinction, as the calculation of patent term changed dramatically in 1995—moving from 17 years from the date of issuance to 20 years from the date of filing.