Prosecution Disclaimer Pitfalls

In Speedtrack, Inc. v. Amazon.com, Inc. (June 3, 2021), the Federal Circuit affirmed not only the district court’s findings relating to patent infringement, but also the importance of prosecution history when interpreting the claims. More specifically, the Federal Circuit affirmed a finding that Amazon.com et al. (“Amazon”) did not infringe U.S. Patent No. 5,544,360. The finding of infringement hinged on whether the district court properly limited claim scope based on the prosecution history of the ‘360 patent – i.e., whether certain claim scope was disclaimed during prosecution.

The ‘360 is owned by Speedtrack and is directed to a computer filing system that enables access to files according to user-designated criteria. The filing system uses folders that contain files with content that overlaps more than one directory.

Representative claim 1 includes a three-step method. At a first step, a “category description table” containing “category descriptions” is created. The category descriptions “hav[e] no predefined hierarchical relationship with such list or each other” (the “hierarchical limitation”). At a second step, a “file information directory” is created as the category descriptions are associated with files. At a third step, a “search filter” is created, which enables searching for files using their associated category descriptions.

The hierarchical limitation of claim 1 of the ’360 patent was added during prosecution to overcome a rejection based on U.S. Patent No. 5,047,918 (“Schwartz”). Schwartz discloses a system that assigns user-definable attributes to data files. To overcome the rejection, applicants successfully argued that Schwartz is a hierarchical system that uses predefined field-and-value relationships where the values associated with each field have a pre-defined relationship to each other, i.e., they all must be of the same type as the field. Applicants explained the predefined field-and-value relationships of Schwartz are different than the claimed “non-hierarchical filing system that allows essentially ‘free-form’ association of category descriptions to files without regard to rigid definitions of distinct fields containing values.”

In reviewing the added hierarchical limitation and associated arguments, the district court concluded that “[t]he prosecution history demonstrates clear and unambiguous disavowal of category descriptions based on hierarchical field-and-value systems.” SpeedTrack stipulated to noninfringement based on such construction because the accused products used field-and-value relationships.

In affirming the district court, the Federal Circuit explained that prosecution disclaimer can arise from either claim amendments or arguments made during prosecution. In the present case, the disclaimer arose from both. To overcome Schwartz, the claims were amended to recite that the category descriptions “hav[e] no predefined hierarchical relationship with such list or each other,” and multiple remarks were made during prosecution arguing that the predefined field-and-value relationships of Schwartz were different that the claimed category descriptions having no predefined hierarchical relationships.

To avoid disclaimer, SpeedTrack argued that during prosecution applicants also distinguished Schwartz on other grounds. However, as the Federal Circuit pointed out, it is established law that arguments and amendments to overcome a reference can still serve as a disclaimer of claim scope even if applicant distinguishes the refence on other grounds. See, e.g., Andersen Corp. v. Fiber Composites, LLC, 474 F.3d 1361, 1374 (Fed. Cir. 2007).

Lessons for Practice

            This case highlights the importance of considering arguments and amendments when prosecution – both in scope and amount. For example, amending and/or arguing a narrow claim scope than is necessary could create undo disclaimer, as could making more grounds of amendment or argument than necessary. For prosecutors, this case is a good reminder that every argument or amendment made during prosecution should be judged for the potential effect it may have in ultimately shaping the outcome of future litigation. For litigators, this case highlights the power of aligning the accused product with the prior art relied on during prosecution to avoid infringement.