Lewin was born in Lodz, Poland. His family fled Poland just ahead of the Nazis in 1939 and arrived in the United States in 1941. Lewin grew up in New York City.
He received his B.A. summa cum laude from Yeshiva College in 1957, and earned his J.D. magna cum laude, from Harvard Law School in 1960, where he was treasurer of the Harvard Law Review. Lewin was law clerk to Chief Judge J. Edward Lumbard of the United States Court of Appeals for the Second Circuit (1960–1961) and to Associate Justice John M. Harlan of the Supreme Court of the United States (1961–1962). Lewin also served as Deputy Administrator of the Bureau of Security and Consular Affairs at the Department of State. He later served as Deputy Assistant Attorney General in the Civil Rights Division of the Department of Justice.
Upon leaving government service, Lewin was a founding partner of Miller Cassidy Larroca and Lewin. Lewin was listed in Best Lawyers in America for Criminal Defense, Business Litigation, and First Amendment Law, was number two in "Washington's Best 75 Lawyers" in the April 2002 edition of Washingtonian magazine, and has been listed in three categories for more than 25 years in "The Best Lawyers in America."
Lewin has practiced law in the District of Columbia, New York, the Supreme Court of the United States, all federal appellate circuits, and many United States District Courts. Lewin has engaged in trial and appellate litigation in federal and state courts for more than 45 years.
