Covington & Burling is bulking up its patent practice on both coasts by recruiting two former judges with the U.S. Patent Trial and Appeal Board.

Peter Chen, who earlier this month left his role as a lead judge at PTAB’s regional office in Silicon Valley, joined Covington this week as a partner in Redwood City, California. Scott Kamholz left PTAB in early 2015 to return to Foley Hoag in Washington, D.C., where he co-chaired the firm’s patent postgrant proceedings practice.