Davis is the great great grandson of Nathan Hughes, an escaped slave who joined the Union Army and fought with the 29th United States Colored Infantry Regiment, was wounded twice, and was the only African American member of the Grand Army of the Republic in Kendall County, Illinois.

He received a Bachelor of Arts degree from Macalester College in 1969 and a Juris Doctor from the University of Minnesota Law School in 1972.

[2] Davis served as a law clerk for the Legal Rights Center from 1971 to 1973.

He was an attorney in the Office of Legal Counsel for the Social Security Administration in Baltimore in 1973, and a criminal defense lawyer for the Neighborhood Justice Center in 1974.

In May 1999, Chief Justice William Rehnquist appointed Davis to serve as a judge on the Foreign Intelligence Surveillance Court.