Over the last several years, the legal doctrine of “prosecution history estoppel” has been a hot topic for U.S. design patent practitioners, the interest and discussion being fueled by several cases that have worked their way to the Court of Appeals for the Federal Circuit (“CAFC”). In the context of utility patents, prosecution history estoppel outlines circumstances when a patent filer is precluded from interpreting the scope of their claims to cover subject matter that has been conceded through narrowing amendments or arguments made during prosecution of the patent application. Before the year 2014, the discussion of prosecution history estoppel in the context of design patents had been sparse. However, in a case of first impression, the CAFC visited the issue of whether prosecution history estoppel applied in the context of design patents in its 2014 opinion in Pacific Coast Marine Windshields Ltd. v. Malibu Boats, LLC, where it held that the principles of prosecution history estoppel also apply to design patents.

During prosecution of the design patent at issue in Pacific Coast, a restriction requirement issued, which identified five patentably distinct groups of designs as windshields with: (1) four circular holes and a hatch; (2) four circular or square holes and no hatch; (3) no holes and a hatch; (4) no holes and no hatch; and (5) two oval or rectangular holes and a hatch. In response, the applicant elected Group 1, corresponding to figure 1, which depicted a boat windshield having four vent holes and a hatch. The remaining four embodiments were cancelled and the amended application issued as U.S. Patent No. D555,070 (“the D’070 patent”). The inventor later obtained a patent for the design with no holes in the corner post as a divisional of the originally-filed application, but no other divisional applications were pursued.

Several years later, Pacific Coast filed a patent infringement suit against Malibu Boats, claiming that Malibu Boats infringed the single embodiment D’070 patent. However, the accused article involved a boat windshield that included three vent holes and a hatch. Having determined that the principles of prosecution history estoppel do apply to design patents, the CAFC then considered whether those principles bar an infringement claim, and put forward a three element test: (1) whether there was a surrender; (2) whether it was for reasons of patentability; and (3) whether the accused design is within the scope of the surrender.

In a recent opinion, issued on August 1, 2018, the CAFC built upon its design patent prosecution history estoppel jurisprudence by issuing an opinion in Advantek Marketing, Inc. v. Shanghai Walk-Long Tools Co. In its decision, the CAFC reversed the summary judgment dismissal of Advantek’s design patent infringement claim by the District Court for the Central District of California, which had previously found that prosecution history estoppel barred Advantek from enforcing its patent.

During examination of the Advantek patent, i.e., U.S. Patent No. D715,006 (“the D’006 patent”), the U.S. Patent & Trademark Office issued a restriction requirement that required election between two groups of figures: (1) Figures 1-4 drawn to a kennel without a cover; and (2) Figures 1-5 drawn to a kennel with a cover. Advantek elected to pursue the first group, canceling Figure 5, and the amended application issued as the D’006 patent.

Advantek subsequently sued its former manufacturer, Shanghai Walk-Long Tools Co. (“Walk-Long”), for design patent infringement and alleged that Walk-Long was copying its commercial kennel product. Walk-Long moved for summary judgment on the pleadings by arguing that since it was selling a kennel with a cover, Advantek was estopped from asserting that the claim of the D’006 patent encompassed Walk-Long’s competing product because Walk-Long’s competing product corresponded with the non-elected embodiment of the asserted D’006 patent. The district court granted the motion and dismissed the complaint, stating that Advantek had surrendered the proposed kennel with a cover to secure a patent by choosing one of two groups of drawings in response to a restriction requirement.

In its appeal, Advantek focused on the third prong of the Pacific Coast test and argued that Walk-Long’s accused design fell outside any claim scope that Advantek may have surrendered during prosecution, arguing that its elected design is the “skeletal structure design,” and that this design is present in the accused kennel, with or without a cover. The CAFC held that regardless of whether Advantak surrendered claim scope during prosecution, a “competitor who sells a kennel embodying Advantek's patented structural design infringes the D’006 patent, regardless of extra features, such as a cover, that the competitor might add to its kennel.”

In essence, this decision reaffirms what many practitioners have known for years, i.e., that an iterative design claiming strategy can be useful for patent prosecutors. For example, by claiming a broad embodiment with portions omitted or dashed, a practitioner can create additional, narrower embodiments that fold in some, or all of the disclaimed subject matter as a fallback position. Further, it should be noted that in some instances, it makes sense to pursue one or more of the narrower embodiments, even after allowance of the broader embodiment, to provide differentiated claim scope or buttress against attempts to invalidate the broader design after assertion in litigation.

But based on the holding in Advantek, if an iterative claiming strategy is not the end goal, then the narrower embodiment(s) can be cancelled with the understanding that the applicant will not necessarily be estopped from asserting the issued design patent against products covered by the canceled, narrower embodiments. However, if the prosecutor's pursuit of the broader embodiment fails in the face of prior art, or the applicant pursues a narrower embodiment first and has no appetite for a divisional application directed to a broader claim, then the doctrine of prosecution estoppel will likely rear its head with significant consequences.