Federal Circuit Summary

Before Prost, Moore and Reyna. Appeal from the District Court of Delaware.

Summary: A limitation in the specification should not be imported into a claim when there is no evidence that the limitation is important, essential or critical.

Blackbird Tech LLC (“Blackbird”) sued ELB Electronics (“ELB”) for infringement of a patent directed to retrofitting existing light fixtures. The district court construed the term “attachment surface” to require the “attachment surface” be secured to the ballast cover in the existing light fixture. Following claim construction, Blackbird stipulated to noninfringement, the district court entered judgment in favor of ELB, and Blackbird appealed.

The Federal Circuit found that the plain language of the claim does not require the “attachment surface” to be secured to the ballast cover. Although the specification disclosed an embodiment securing the “attachment surface” to the ballast cover, there was no evidence that such a limitation is important, essential, or critical to the invention. Importantly, a limitation requiring that the attachment surface be secured to the ballast cover was removed during prosecution, indicating to a person of skill that a fastening mechanism securing the “attachment surface” to the ballast cover is not required by the claim. Moreover, the Federal Circuit explained that, as an apparatus claim, reciting how the lighting apparatus is installed to achieve its “retrofit” is not necessary. Accordingly, the Federal Circuit adopted Blackbird’s construction, vacated the district court’s entry of judgment of noninfringement, and remanded for further proceedings.

Judge Reyna dissented, reasoning that in the context of the specification and limiting preamble, the claim implicitly requires that the “attachment surface” be secured to the ballast cover to achieve the retrofit function. Moreover, Judge Reyna argued that the majority’s construction may render the patent invalid for lack of written description and enablement.

This case is: BLACKBIRD TECH LLC V. ELB ELECTRONICS, INC.

Editor: Paul Stewart

Written by: Shuchen Gong and Karen M. Cassidy