Lehrman began his professional career as a corporate attorney with the Minneapolis law firm of Larkin, Hoffman, Daly & Lindgren. He further developed his corporate legal practice as a Partner with the St. Louis law firm of Gallop, Johnson, and Neuman. Before founding Portage in 1993, he was the national director of the Social Investment Forum, an association of institutional portfolio managers and financial professionals that directed capital to socially responsible businesses.

Lehrman has lectured extensively on business and legal issues associated with venture capital, corporate finance and business law at the University of Minnesota Business & Law Schools, University of St. Thomas MBA program, and other professional associations.

Lehrman has dedicated a significant portion of his professional career to community issues. He served as a board member of the then Minnesota Advocates for Human Rights (1996-2000); Executive Committee, (1999-2000) and through that organization received two prestigious International Human Rights Recognition Awards in 1993 and 1997. He also served as a board member (1994-2002) for the Jewish Family and Children's Service.

Lehrman currently serves on the Board of Trustees of Adath Synagogue, and acts as a special advisor to the Board of the Minneapolis Jewish Communty Center. He is a member of the Minnesota Venture Capital Association, the Minnesota State Bar Association, and serves on the University of Minnesota Business Advisory Council. Lehrman also is on the steering committee of the Minnesota Military Appreication Fund and serves on the board of the Minnesota Genocide Intervention Network.

Lehrman graduated from Carleton College (Northfield, Minnesota) in 1977 with a B.A. in economics and received a J.D. from William Mitchell College of Law (St. Paul, Minnesota) in 1981. In 2002-2003, he completed a specialized graduate course for Venture Capitalists at the Unviersity of Minnesota Medical School.