Prosecution History Estoppel in Design Patents

Recently decided Pacfic Coast Marine Windshields, Ltd. v. Malibu Boats, LLC established, perhaps predictably, that prosecution history estoppel is a doctrine that can be enforced in design patent litigation.

Prosecution history estoppel is the practice of defending a patent litigation suit by arguing that the patent owner surrendered some scope of protection during the examination and processing of the application that became a patent, and that that scope would have covered your product. In other words, the defense asserts that the very product that it makes was one which the patentee attempted to patent, but couldn’t because it wasn’t patentable, and so carved out of its application in order to get the patent to grant. By carving it out, the patentee surrendered that subject matter to the public for anyone to make and use.

Previously, this doctrine was only used in utility patent cases. However, the Pacific Coast case made clear that it also holds true in design cases. Design patent applications are often filed with multiple embodiments, and the Patent Office frequently issues a restriction requirement stating that the different embodiments are too different to be included under one application and thus must be divided out. If the applicant removes the extra embodiments from the application and doesn’t later file divisional applications to those embodiments, prosecution history estoppel may establish that the extra embodiments were surrendered.

Indeed, this is just what happened in Pacific Coast. There, the Pacific Coast boat windshield company filed a design application for a number of windshield designs including some with round holes in the frame, some with square holes, some with oblong holes, as seen below. The Patent Office issued a restriction requirement, and Pacific Coast elected just one design, which had four round holes. Pacific Coast later filed one divisional application to another design, but not divisionals on all the designs.

design patent

Malibu Boats later began manufacturing a windshield with three oblong holes in the frame, similar to one of the designs on which Pacific Coast had originally filed but did not follow up with a divisional. The trial court held that Pacific Coast did commit prosecution history estoppel and that the Malibu Boats’ design was within the scope of the surrendered subject matter. On appeal, the Federal Circuit agreed on the prosecution history estoppel, but said that the subject matter was not the same.

In light of this case, clients may sometimes find that it is better to file multiple embodiments of designs in separate, individual design applications, rather than combining them into one. Doing so can reduce the risk of prosecution history estoppel, which would otherwise force an applicant to restrict out different embodiments from a single application and then chase each one with a divisional lest it risk surrendering that embodiment to the public. However, this can be a costlier approach up front. Careful thought and consideration should be undertaken when deciding how to file multiple embodiments.