Appeal from the United States District Court for the Western District of Washington in No. 09-CV-0586, Judge Ricardo S. Martinez.
LAWRENCE D. GRAHAM, Lowe Graham Jones, PLLC, of Seattle, Washington, argued for plaintiff-appellee.
BENJAMIN J. BYER, Davis Wright Tremaine LLP, of Seattle, Washington, argued for defendant-appellant. With him on the brief was STUART R. DUNWOODY.
Before MOORE, CLEVENGER, and REYNA, Circuit Judges.
Moore, Circuit Judge.
Defendant ARB Corporation Ltd. (ARB) appeals from the district court's grant of summary judgment of non-infringement of U.S. Patent No. 5,591,098 (the '098 patent) to Ring & Pinion Service, Inc. (R& P). Because the district court erred by improperly applying the doctrine of claim
vitiation, we reverse and remand with instructions to enter judgment of infringement for ARB.
The invention claimed in the '098 patent is an improved automobile locking differential. '098 patent col. 1 l. 63--col. 2 l. 2. A differential is a mechanism that allows wheels to rotate at different speeds relative to each other. When locked, a locking differential distributes torque from the engine such that both wheels spin at the same rate. Claim 1 is representative:
A locking differential comprising
a differential ...