Dennis M. Flannery joined the firm in 1968 and was a partner in the Litigation Department from 1973 to his retirement in 1999. He has served as the Coordinator for Litigation Associate Training and was Chair of the Charitable Contributions Committee. Currently, he conducts the firm’s moot court program, lectures on deposition practice, and administers oral communications workshops. Mr. Flannery was the 2007 recipient of the firm's Jerome P. Facher "Award for Excellence in Training," which honors exceptional commitment to the professional development and training of other attorneys.

Following his United States Supreme Court clerkship with Chief Justice Earl Warren (1964 Term), Mr. Flannery served in the United States Army (1965-1967), from which he was honorably discharged with the rank of Captain. In addition to his private law practice experience, Mr. Flannery was affiliated with the Center for Law and Social Policy from 1971-1973, where he argued the Trans-Alaska Pipeline case before the United States Court of Appeals for the District of Columbia Circuit (en banc) and the United States Supreme Court.