Federal Circuit Affirms Non-Infringement in NG LLC v. CreatedHair Designs: Prosecution History Estoppel Precludes Claim Scope Expansion
“Doctrine of equivalents barred by NG’s prior claim amendments”
The United States Court of Appeals for the Federal Circuit (CAFC) has upheld a summary judgment of non-infringement in the case of NG LLC v. Created Hair Designs, LLC, reinforcing the principle that statements made during patent prosecution can limit a patentee’s ability to later broaden claim interpretation through litigation. At issue was the construction of a key claim term in two patents owned by NG LLC and whether the doctrine of equivalents could be invoked despite prior prosecution history.
Background of the Dispute
NG LLC holds U.S. Patent Nos. 10,945,477 and 10,881,159, both of which relate to a wig grip apparatus incorporating a mesh element. Central to both patents is Claim 1, which specifies “the mesh element includes a forward periphery” and that “the wig grip apparatus terminates at the forward periphery.” NG initiated legal proceedings alleging infringement of these claims. However, the U.S. District Court for the Central District of California granted summary judgment in favour of Created Hair Designs, finding no literal infringement and further concluding that the doctrine of equivalents was unavailable due to prosecution history estoppel.
Claim Construction Dispute
At the heart of the litigation was the interpretation of the phrase “the wig grip apparatus terminates at the forward periphery.” NG argued that this term should be given its “plain and ordinary meaning,” asserting that it simply indicates where the apparatus ends, without precluding the possibility that other components may extend beyond the mesh element’s forward periphery. The district court, however, interpreted the term to mean that “the forward periphery of the mesh element is the most forward portion of the wig grip apparatus,” thereby limiting the apparatus so that no component—including securement members—could extend beyond that boundary.
Federal Circuit Analysis
The Federal Circuit affirmed the district court’s construction, emphasizing that the claim language and specification together clearly supported the interpretation that the entire wig grip apparatus terminates at the mesh element’s forward periphery. In particular, the court noted that the securement members referenced in the specification were described in alignment with the forward periphery. For example, it was highlighted that “the securement members 108 and 114 may each include a forward edge 126,” and that “the forward periphery 132 may preferably be in alignment with the forward edges 126.” This consistency between the claim language and the specification reinforced the district court’s interpretation.
Impact of Prosecution History
A pivotal factor in the CAFC’s decision was the role of prosecution history estoppel. During patent prosecution, NG had amended the claims to distinguish them from prior art by expressly introducing the limitation that “the wig grip apparatus terminates at the forward periphery.” Originally, NG had included language stating that “the wig grip apparatus lacks non-transparency beyond the forward periphery,” which the examiner found unclear. NG then accepted a revised formulation— “terminates at the forward periphery”—to overcome both § 112 objections and prior art rejections. The Federal Circuit held that this amendment was made for a substantial reason related to patentability. As such, NG could not later invoke the doctrine of equivalents to reclaim coverage it had explicitly surrendered during prosecution.
Rejection of Doctrine of Equivalents Argument
NG attempted to argue that prosecution history estoppel should not apply because the amendment was only “tangentially related” to the asserted equivalent. However, the Federal Circuit was unpersuaded. It emphasized that NG had explicitly identified the extension of the mesh section to the forward edge as a distinguishing feature during prosecution. This, the court held, directly contradicted NG’s attempt to now capture equivalents that would extend beyond that very boundary. The court concluded that NG was precluded from reclaiming claim scope that had been surrendered to secure patent allowance.
The Federal Circuit’s decision affirms the importance of clear and consistent claim construction and highlights the limiting effect of prosecution history estoppel. By aligning with the district court’s claim interpretation and rejecting NG’s attempt to use the doctrine of equivalents, the court emphasized that patentees cannot recapture through litigation what was deliberately given up during prosecution. The judgment of non-infringement in favour of Created Hair Designs was thus upheld, reinforcing established principles of patent claim interpretation and estoppel in U.S. patent law.