November/December 2024
IP Litigator
By J. Derek McCorquindale; David N. Lefcowitz; Matthew C. Berntsen
Courts have often excluded evidence of prior post-grant proceedings filed by third parties because of its potential to cause unfair prejudice, confuse the issues, or mis- lead the jury. In Delaware, for example, Judge Andrews in Nox Med. Ehf v. Natus Neurology Inc. held that “[f]ailure to institute an IPR has little or no probative value, and, to the extent there is any probative value, it is greatly outweighed by the risk of jury confusion and the time it would take to put the failure to institute in an appropriate context.”[1] And in ART+COM Innovationpool GmbH v. Google Inc., the Delaware district court noted that post-grant proceedings are “reached on a record that was less than complete and without the benefit of a full adversarial proceeding,” raising a further reason to preclude such evidence before the jury.[2] Other trial courts around the country have held similarly when facing the question.[3] But there is some contrary case law emerging in certain circumstances.[4]
Recently, in IBM v. Zynga Judge Williams of the District of Delaware found that evidence of a USPTO decision denying institution may be relevant where the defendant is relying on the same prior art relied on by the unsuccessful third-party IPR petitioner.
Plaintiff IBM intended to introduce evidence about a non-instituted IPR brought by a different party to argue to the jury “that [its] patent has been battle-tested.”[5] Zynga filed a motion in limine seeking to “exclude argu- ment, evidence, or testimony regarding post-grant Patent Office Proceedings,”[6] contending that they are not relevant and unduly prejudicial.
Judge Williams granted-in-part and denied-in-part Zynga’s motion.[7] He recognized that the courts in Nox and ART+COM refused to allow evidence of prior IPR proceedings.[8] But he also noted that, in this case, some of the prior art Zynga was relying on for its invalidity defense had also been considered by the USPTO when it declined to institute the third-party IPR. This overlap in prior art, reasoned Judge Williams, distinguished this case from Nox and ART+Com.[9] Accordingly, Judge Williams held that, although the evidence of the non- instituted IPR would normally not be allowed, if Zynga decides to rely on that same prior art, then IBM would be allowed to bring in evidence of the non-instituted IPR.[10]
In reaching his conclusion, Judge Williams cited Willis Elec. Co., Ltd. v. Polygroup Ltd. and L.C. Eldridge Sales Co. v. Azen Mfg. Pte., Ltd., for the proposition that certain circumstances justify permitting a jury to hear such evidence from earlier post-grant proceedings.[11] Willis held that the patentee could introduce evidence of a prior IPR where the defendant relied on a combination of prior art that “closely tracks what was considered and rejected by the PTAB.”[12] The Willis court found that similarity of invalidity theories “provides a legally meaningful basis for the jury to weigh against [the defendant’s] invalidity case.”[13] The Eldridge court determined that the “risk of confusion is minimal” in showing the jury evidence of a prior unsuccessful IPR “because a lower threshold of proof is required to show invalidity before the USPTO than is required by the Defendants in [district court].”[14] That is, because the USPTO applies a preponderance of the evidence standard for unpatentability, which is lower than the clear and convincing evidence standard that district courts require to demonstrate invalidity. In other words, if a patent survives an IPR proceeding and remains valid under the lower evidentiary standard, the risk of confusion to a jury should be minimal when validity of the same patent is considered under a higher standard at the district court. Accordingly, Judge Williams held that “if Zynga opens the door by introducing prior art raised before the Patent Office, IBM may respond by introducing- ing evidence related to the post-grant proceedings.”[15]
It will be interesting to see the effect of the District of Delaware’s ruling in Zynga, as there is some ambiguity as to how far the order was intended to reach. On the one hand, there is precedent for finding that a defendant’s use of a combination previously rejected by the PTAB may render evidence of the prior post-grant proceeding relevant.16 On the other, a broad reading of the Zynga decision could mean that a defendant’s use at trial of any prior art presented to the Patent Office in any context renders any prior proceeding involving that art relevant, which has the potential to significantly complicate future patent infringement defendants’ decision-making as to what prior art to present at trial. Other courts will likely have to draw these lines if the Zynga case is cited by litigants for the broadest possible application in future disputes.
United States Patent and Trademark Office (USPTO), prior art, jury trial, District of Delaware, likelihood of confusion
Hybrid Conference
Intellectual Property Law Institute 2026 – California
October 19-20, 2026
San Francisco
Hybrid Conference
Intellectual Property Law Institute 2026 – New York
September 28-29, 2026
New York
Due to international data regulations, we’ve updated our privacy policy. Click here to read our privacy policy in full.