Statements Made in Litigation Can Support Prosecution History Estoppel

In Speedtrack, Inc. v. Amazon.com, Inc., Nos. 2020-1573, 2020-1660 (Fed. Cir. June 3, 2021), the Federal Circuit affirmed the District Court for the Northern District of California’s final judgment of noninfringement based on claim construction.

Speedtrack’s patent, U.S. Patent No. 5,544,360, is directed to a method of organizing computer files. The user assigns each file one or more category description, which is later used to locate the file. For example, a recipe file can be assigned “French,” “Bread,” and “Recipes,” whereas the pertinent prior art, U.S. Patent No. 5,047,918 (“Schwartz”), has a hierarchical structure requiring an “attribute” such as “recipes” and a “value” such as “bread.”

The Federal Circuit affirmed the district court’s finding that the patentee disclaimed the use of hierarchical structures within its category descriptions. During the prosecution, Speedtrack argued that Schwartz’s hierarchical structure “fell outside the scope of the amended claims” and narrowed the claims by adding the limitation “the category descriptions having no predefined hierarchical relationships….” During the litigation, Speedtrack argued that the claim was amended to distinguish from Schwartz. The Federal Circuit held that these statements are sufficient to find a clear and unmistakable disclaimer of the claim scope.