Gardner was born in Allentown, Pennsylvania, on September 14, 1940.

He received a Bachelor of Arts degree magna cum laude from Yale University in 1962 and a Juris Doctor from Harvard Law School in 1965.

Naval Reserve JAG Corps officer from 1969 to 1993 and retiring as a Captain.

He was an Assistant District Attorney of Lehigh County from 1972 to 1977, and then First Assistant District Attorney of Lehigh County from 1977 to 1981.

On April 22, 2002, Gardner was nominated by President George W. Bush to a seat on the United States District Court for the Eastern District of Pennsylvania vacated by Jan E. DuBois.