Judge Leonard Stark recently granted a patent infringement defendant’s motion to amend its answer and counterclaims to assert counterclaims of inequitable conduct. See Intervet Inc. v. Boehringer Ingelheim Vetmedica, Inc., C.A. No. 11-595-LPS (D. Del. Oct. 9, 2012). The defendant represented that it could not have known of the facts supporting a claim of inequitable conduct by the deadline for amending the pleadings, and therefore the good cause required by Rule 16 to amend the case schedule existed. Specifically, the defendant was unaware that the inventors knew the materiality of certain prior art that they had not disclosed to the PTO until after an inventor notebook was produced and depositions of two other inventors were taken. Given these circumstances, Judge Stark found that the defendant had “acted diligently in gathering evidence to support its inequitable conduct claim and informed [the plaintiff] of its intention to amend its answer approximately one week after [the relevant] deposition.” “The Court [did] not find undue delay, bad faith, or dilatory motive in [the defendant’s] actions . . . [and the] amended claim [was] not futile.” Furthermore, the Court was “not persuaded that [the plaintiff] will be unduly prejudiced if the Court grants [the] motion . . . [as] discovery appears to be ongoing.” Accordingly, Judge Stark granted the motion to amend the answer and counterclaims.