Lloyd Weinreb received bachelor's degrees from Dartmouth College and Oxford University, and graduate degrees from Harvard Law School and Oxford University.

Prior to beginning his teaching career, Weinreb served as a clerk for Justic Harlan on the US Supreme Court in 1963 and as a criminal prosecutor in Washington, D.C. 

His research interests include criminal law, criminal procedure, intellectual property, and legal and political philosophy.

Lloyd Weinreb has an extensive bibliography and has authored several casebooks on criminal law, as well as many law review articles.

Despite lacking the celebrity professor status of some of his colleagues at Harvard Law School, Professor Weinreb is highly regarded by students and faculty. He has been described as "a remarkable model of competence and clarity". The Harvard Law Record ranked him among the 'ten professors whose classes you won't want to miss'.