Long known for its litigation prowess, Boies, Schiller & Flexner is adding to its small corporate group to fill a hole left by the departure last year of partner Richard Birns for Gibson, Dunn & Crutcher.

Corporate and project finance expert Dev Sen was officially elected to Boies Schiller’s partnership Monday. He joins the firm after three years as a partner at O’Melveny & Myers, having escaped to the latter in May 2012 just prior to the historic collapse of Dewey & LeBoeuf, where Sen once served as co-chair of the diversity committee at the now-defunct firm.