Heller Ehrman Silicon Valley partner Hal Milstein is leaving the firm to join West Coast rival Sheppard Mullin Richter & Hampton.
The news comes amid continued speculation over the future of Heller. Earlier this month the firm's talks with Baker & McKenzie broke down. The firm is currently believed to be in talks with at least three firms, including Mayer Brown.
Milstein's practice focuses particularly on trademark counselling and prosecution services, particularly in the life sciences and high technology industries.
The IP specialist is the latest in a long line of Heller partners to leave the firm in recent months, and the seventh to join Sheppard Mullin since January.
Other partners who have joined Sheppard Mullin include New York IP partner Blaine Templeman, Los Angeles litigator Darryl Snider, labour and employment partner Jonathan Stoler, and finance and bankruptcy specialists Carren Shulman and Russell Reid.
Heller spokesman Patrick Bustamante said: "We consider Hal to be a good lawyer and colleague, and we wish him well. Heller Ehrman has an active IP practice with approximately 100 lawyers. We will continue to handle trademark and other IP matters for clients in Silicon Valley and around the world."
Milstein was a pharmacist before going to law school, and spent 10 years in-house as trademark counsel for pharmaceuticals companies Syntex and Sandoz before joining Heller in 1999.