Proskauer Rose has opened a branch in Boston after a triple-partner raid on local firm Testa Hurwitz & Thibeault, with the New York firm pledging to grow its new office to 20 lawyers by the end of the year.

The 600-lawyer firm has hired partners Steven Bauer, one of the founders of Testa Hurwitz’s IP practice, Joseph Capraro and Daniel Bernstein to launch the base.