When amending patent claims during prosecution, practitioners must ensure all changes adhere to 35 U.S.C. § 112(a)’s written description and enablement requirements. Amendments must derive explicit or inherent support from the original specification and figures, avoiding the introduction of new matter. As emphasized in 37 CFR 1.83, every element in the claims must be illustrated in the drawings unless otherwise justified. Failure to anchor amendments in the original disclosure risks creating ambiguities that examiners may exploit under the USPTO’s Broadest Reasonable Interpretation (BRI) standard, even if the claims avoid § 112 rejections.
In this vein, while the USPTO applies BRI to claims during examination, examiners occasionally stretch interpretations beyond what the specification supports, particularly when doing so enables an easier rejection in view of the cited art (as broader claims are more likely to read on the prior art). When the support for an element, particularly one amended during prosecution, is minimal, this opens the door to potentially unintended interpretations.
Consider a recent PTAB case. Appeal 2024-000224, Application 17/253,419. The invention relates to a vacuum cleaner innovation owned by Bissel, where the vacuum cleaner has a headlight array providing a beam parallel. The independent claim on appeal is provided below:
24. A vacuum cleaner, comprising:
a base assembly defined at least in part by a base body having a lowermost edge and including a suction nozzle;
a hand-held portion having a hand grip and a suction source in fluid communication with the suction nozzle and configured for generating a working airstream;
a working air path from the suction nozzle to an air outlet in the hand-held portion and including the suction source; and
a headlight array located at the lowermost edge of the base body along a forward oriented portion thereof,
providing a beam that is substantially parallel to the surface to be cleaned and spaced above a plane extending along a bottom of the base assembly and parallel to the beam, the beam being spaced at not more than 30 mm above the plane.
At issue was the claim limitation of a headlight array located at the lowermost edge of the base body along a forward oriented portion thereof. The applicant contended that the prior art was defective because the array was positioned at a central vertical position on the front surface of the housing and not at the lowermost edge of the base body. That limitation was amended during prosecution, previously referring to a “lower” edge, as opposed to the amended language of a “lowermost” edge.
To determine the proper interpretation of the claim term (since there was no rejection under 112), the board looked to the specification (which only used the term “lower” and never used the term “lowermost”).
Problematically for the applicant, the specification described a headlight array and a front bar on which the array was positioned as being a lower portion of the base assembly, and further showed in the drawing that there was actually a lip of the lowest edge of the front bar that protrudes below the headlight array such that the headlight array rests slightly above the lowest edge of the base assembly.
Given this disclosure, as well as other disclosure creating similar issues, the Board determined the proper interpretation in light of the specification was that the headlight array is located in a low position along the front surface of the base assembly such that the headlights project illumination at substantially a horizontal projection along the surface to be cleaned. From there, it was an easy application of the broadened claim interpretation to confirm that the prior art satisfied the claim element.
This case illustrates how even though the claim amendment was accepted by the examiner and expressly required a specific structure that seemed to distinguish the cited art, the lack of support in the specification opened the door to a broader interpretation so as to encompass the prior art. While the board could have gone a different way that included rejecting the limitation as lacking support, that would have necessitated a new ground of rejection, with all of the procedural options that entails, making it potentially less attractive to the board.
While this is just one example of issues that can arise with amendments having dubious support, it is by no means exhaustive. One can consider other issues, such as creating vulnerabilities that can be exploited in post-grant review or infringement proceedings, to name just a couple.