Unsupported Assertions: Expert's Persuasive Authority Suffers Without Directly Engaging Claim Limitations

An expert asserting that a patent claim reciting different features than the prior art is nonetheless "equivalent" to the prior art must address and account for the recited limitations head-on, or otherwise lose persuasive authority.

In Elbit Systems of America, LLC v. Thales Visionix, Inc., No. 2017-1355 (Fed. Cir. Feb. 6, 2018), the patent-at-issue related to motion-tracking systems that first calculate tracking and reference signals and then determine a "relative angular rate signal" to calculate relative orientation of an object with respect to a moving reference frame. Slip op. at 3-4. The petitioner expert argued that the claimed two-step method was obvious over the prior art, including a prior art motion-tracking system using a three-step method, first calculating the object's orientation relative to an inertial reference frame, then calculating the orientation of the moving reference frame relative to the inertial reference frame, and then resolving the two