After earning a bachelor's in political science from Dartmouth College, Michael A. Millemann enrolled at Georgetown Law, where he served as co-chair of the Law Students Civil Rights Research Council while completing his juris doctor. Early in his career, Michael A. Millemann held positions with the ACLU National Prison Project, Baltimore Legal Aid, and Multnomah County Legal Services, in Oregon.

Aside from a two-year absence from 1979 to 1981, during which he served as chief general counsel of the Maryland Office of the Attorney General, Michael A. Millemann has taught law students at the University of Maryland since 1974. In addition to general classroom courses in subjects such as criminal law, criminal procedure, and trial practice, he has developed and taught numerous experimental courses.

Supplementing his work in the classroom, Millemann has co-authored numerous book chapters and articles and served on various Maryland-based legal committees and councils, including the Baltimore City Bar Association's Legal Services Committee and the Maryland State Bar Association's Correctional Reform Section.

Millemann also has received many awards over his career, including several best teacher awards, state and national awards for public interest and pro bono (free legal work). He also has led in the creation of many public interest programs, including those that provide free legal services to the poor, engage high school students in community improvement projects, and protect the environment, including the Chesapeake Bay.