Understanding Google versus Sonos and its patent prosecution implications

Understanding Google versus Sonos and its patent prosecution implications

Developed as a judicially-created doctrine, prosecution laches intended to prevent egregious delays in prosecution at a time when prosecution could, in theory, extend indefinitely.

The U.S. Court of Appeals for the Federal Circuit issued its long-awaited decision in Google LLC versus Sonos, Inc., providing guidance on the doctrine of prosecution laches. As the first Federal Circuit decision on prosecution laches for a patent issued after 1995—when patent terms changed from 17-years-from issuance to 20-years-from filing—some suspected the Federal Circuit might definitively end the prosecution laches doctrine. While prosecution laches remains a valid equitable defence, the Federal Circuit placed considerable limitations on its applicability.

Developed as a judicially-created doctrine, prosecution laches intended to prevent egregious delays in prosecution at a time when prosecution could, in theory, extend indefinitely. An accused infringer to assert prosecution laches as a defense, must prove: (1) “unreasonable and unexplained delay in prosecution that constitutes an egregious misuse of the statutory patent system under the totality of the circumstances” and (2) “prejudice attributable to the delay.”

The Federal Circuit’s decision focused on the question of ‘prejudice’. An accused infringer cannot claim to be prejudiced by prosecution delays if the relied-upon subject matter supporting the asserted claims was published before the accused infringer began its work and investments in the accused technology; the court found. The non-precedential decision is sweeping and blunt in the context of the specific facts of the case but leaves several questions as to which circumstances would give rise to a viable prosecution laches defense.

The Federal Circuit’s decision relies on the fact that Google’s investment in the accused technology allegedly began sometime in 2014 or 2015, after the 2013 publication date of the earliest patent application in the asserted patent’s family. Id at *7. Although the asserted claims were actually filed after Google’s alleged intervening rights, the Federal Circuit determined that Google could not be prejudiced by the later continuation patents because it knew about the patent family and what subject matter might be claimed in the future.

The non-precedential decision of the court, however, does not hold that prosecution delays can never be “prejudicial”. The question as to what circumstances would give rise to a successful prosecution laches defense remains.

Further, the Federal Circuit’s focus on when Google received proper notice of the relied-upon disclosure makes continuations an outlier compared to other aspects of patent law.

Also, a court could potentially find it prejudicial for an applicant to correct defects in the priority claim of a continuing application after the application has published.

And a late correction to the priority claim could be accompanied by an incorporation of subject matter from the earlier patent’s disclosure. In that case, though all the resulting subject matter was technically published before it was properly incorporated into the later application, its incorporation may allow the applicant to get claims of a scope that the accused party could not have expected at the time of its investment activities. This type of unforeseeable claim scope could be exacerbated for applications that have a complex priority chain to applications having non-overlapping disclosures.