In patent litigation governed by local patent rules, a party claiming infringement must usually serve a “Disclosure of Asserted Claims and Infringement Contentions.” This disclosure must sufficiently identify each claim and the infringing product or process of the opposing party. Jurisdictions, however, have different standards for sufficient disclosures and courts have substantial discretion in determining the disclosing party’s obligations. In Times Three Clothier, LLC v. Spanx, Inc. (pdf), 2014 WL 1795210, *4 (S.D.N.Y. May 6, 2014), Judge Cote denied an amended infringement contention that directly contradicted a prior contention because there was no longer an inference of infringement. On October 29, 2013 Times Three received a patent describing women’s shapewear in which the middle section included a more compressive material than the upper or lower sections. That same day, Times Three brought an infringement action against two of Spanx’s products claiming that they followed the same design with high compression mid-sections and lower compression outer sections. Times Three incorrectly referred to the waist lining of the Spanx product as the middle (with 64% spandex) and the body section as the top (with 20% spandex). On February 4, 2014, Spanx advised Times Three that the waist lining was actually the lower section of the garment with the body being the middle. In response, Times Three reversed its contention to state by amendment that the body section had more compression material than the waist lining and removed its supporting citations. In light of the reversal, Spanx filed a motion to strike Times Three’s amendment. In its reasoning, the Court determined that “where information is reasonably available to plaintiffs before discovery, infringement contentions must be sufficient ‘to raise a reasonable inference that all accused products infringe’ and to permit the Court to ‘make a principled decision on whether discovery will proceed.’” Because Times Three’s initial contentions now supported a finding of non-infringement, the court stayed the case on the applicable patent and found that more detailed infringement contentions were required before discovery could proceed.” The court noted that this was not an issue of unknown discovery because the products were publicly available at low cost. Key Takeaway: Plaintiffs should be careful when asserting an amendment to an infringement contention that is contrary to their original claim. If new facts create contradictory positions between the original and amended infringement contentions, the amended claims should be sufficiently detailed to justify the contradiction and provide adequate support for their assertions. The author thanks Josh Nosal, a student at the University of Texas School of Law, for his assistance in writing this post.