Polsinelli recently secured a significant victory on behalf of its clients WeatherTech Direct, MacNeil Automotive Products Limited and MacNeil IP, the companies behind the globally recognized WeatherTech^® brand of vehicle accessories, in a long-running intellectual property dispute against foreign competitors accused of misappropriating MacNeil’s innovations.

MacNeil brought claims including patent infringement, and following extensive motion practice, the Honorable Judge Thomas S. Zilly of the U.S. District Court for the Western District of Washington sided with Polsinelli’s arguments that the defendants are barred from asserting an invalidity defense to MacNeil’s patent infringement claims, based on the doctrine of inter partes review (IPR) estoppel and MacNeil’s earlier favorable IPR outcome.

This ruling is especially notable in light of ongoing debates over the scope of IPR estoppel. While the Federal Circuit’s recent 2025 decision in Ingenico Inc. v. IOENGINE, LLC suggested that estoppel may not extend to invalidity arguments grounded in prior public use or sale, Judge Zilly adopted Polsinelli’s position that estoppel does apply when such prior-use evidence is offered as part of an obviousness theory that is not materially different from arguments already raised in the IPR. This is an important decision not only for MacNeil but also for the development of IPR estoppel law. It provides a clear roadmap for other plaintiffs seeking to prevent defendants from circumventing estoppel by reframing invalidity arguments around prior use.

This outcome reinforces Polsinelli’s reputation as a leader in intellectual property litigation and highlights the firm’s commitment to protecting the rights of innovators like WeatherTech^® in highly contested disputes.

The Polsinelli team members primarily responsible for the estoppel motions include Shareholders Timothy M. Schaum (Chicago), Patrick T. Muffo (Chicago) and James P. Murphy (Houston) with many more team members supporting the overall litigation and IPR efforts on behalf of MacNeil.