[2] He left Bell Labs to enroll at Harvard Law School, where he earned a J.D., cum laude, in 1991.
In 1994, Mack left the practice of law to enter graduate school at Princeton University, where he received a master's degree in 1996, and a Ph.D. in 2005, both in history.
In 1999, Mack received an appointment as the Reginald F. Lewis Fellow at Harvard Law School.
Mack's teaching and scholarship have focused on the legal and constitutional history of American race relations and economic life.
[3] In 2010, he was awarded an honorary Doctor of Public Service by Harrisburg University of Science and Technology.