A district court judge recently denied a motion to strike portions of an accused infringer’s invalidity contentions that relied in part on publications that the accused infringer had not raised in connection with an IPR petition.  Star Envirotech accused Redline Detection of infringing Star’s patent number 6,526,808, which claims methods for detecting leaks.  Redline subsequently filed a petition for inter partes review of two of the asserted claims, arguing that the claims were unpatentable over certain prior art publications.  The PTAB ultimately determined that Redline had failed to demonstrate that the challenged claims were unpatentable.

In the district court litigation, Redline served invalidity contentions that cited seven references relating to the “LeakMaster,” a prior art machine that Redline alleged had been sold and/or publicly used more than a year prior to the filing date of the ‘808 patent.  Star moved to strike the references from Redline’s invalidity contentions, arguing that the references were subject to the estoppel provisions of 35 U.S.C. § 315(e)(2).  Under the statute, if an inter partes review results in a final written decision, then the petitioner may not assert in a civil lawsuit any invalidity contention based on grounds that the petitioner reasonably could have raised in the inter partes review. 

According to Star, Redline could have raised the references, which included an instruction manual for the LeakMaster, during the inter partes review.  Redline argued that the actual prior art at issue was the LeakMaster machine itself, and Redline could not have raised the machine as prior art in the IPR, which is limited to patents and printed publications.  According to Redline, the machine itself disclosed features claimed in the ‘808 patent that were not disclosed in the related documents, including the instruction manual.  Redline further argued that the machine was properly combined with the new references to form new grounds of invalidity.

The court agreed with Redline, citing examples of claim limitations that may be disclosed by the machine but not the instruction manual.  Accordingly, the court denied Star’s motion to strike the references from Redline’s invalidity contentions. 

The issues addressed in this case warrant attention from defendants in patent infringement suits.  Under the court’s ruling, accused infringers can assert invalidity contentions by combining prior art products with prior art publications—even if those publications were not raised during an inter partes review of the same patent claims.

The case is Star Envirotech, Inc. v. Redline Detection, LLC et al., Case No. 12-CV-01861 in the Central District of California.