Prosecution History: A Patentee's Silence Can Be Motivating

In Elekta Ltd. v. ZAP Surgical Systems, Inc., the Federal Circuit affirmed a Patent Trial and Appeal Board decision in an inter partes review that invalidated patent claims relating to "a device for treating a patient with ionizing radiation for certain types of radiosurgery and radiation therapy."¹ 81 F. 4th 1368, 1370 (Fed. Cir. 2023) (affirming ZAP Surgical Sys., Inc. v. Elekta Ltd., IPR2019-01659, paper 48 (Mar. 30, 2021)).

One of the central issues in Elekta was whether the Board had substantial evidence for finding that a skilled artisan would have been motivated to combine two prior-art references, even though one pertained to "an imaging device" (the Grady patent) and the other to "a radiation device" (the Ruchala publication). 81 F. 4th at 1373. The Board based its decision, in part, on the '648 patent's prosecution history.