Piggy Pushers, LLC v. Skidders Footwear, Inc.

Whether a claim’s preamble limits the claim’s scope is determined on a case by case basis, considering the claim as a whole and the invention described in the patent. Where the preamble’s terms state a fundamental characteristic of the invention, the preamble limits the claims.

Opinion (Per Curiam): Piggy Pushers, LLC ("Piggy Pushers") owns US Patent No. 6,385,779, which covers an infant sock with gripping surfaces that enhance traction for an infant while she is walking or crawling. Piggy Pushers sued Skidders Footwear, Inc. ("Skidders") alleging Skidders' infant shoe infringed the ‘799 patent. The District Court for the Western District of Michigan construed the patent claims, finding that the preamble to each of the patent’s claims limited the claims to socks. Following claim construction, the district court granted Skidder’s motion for summary judgment of noninfringement. Piggy Pushers appealed. On appeal, claim construction and grants of summary judgment are reviewed de novo. Whether a claim’s preamble limits the claim scope is determined on a case by case basis considered in light of claim as a whole and the invention patented. Where the preamble states a requirement that is a “fundamental characteristic of the claimed invention” the preamble limits the claim. Because the specification distinguished a sock from a shoe, noting that a shoe can be hard to put on an infant, the Federal Circuit agreed with the district court that specification narrowed the patent’s claims to cover only a sock and not a shoe. Although the Federal Circuit found the district court’s construction of the term sock incomplete, it never the less agreed that Skidders’ product (which has a rubber outsole) was not a sock, and therefore was not covered by the patent’s claims. Accordingly, the Federal Circuit AFFIRMED the District Court’s grant of summary judgment of noninfringement.