He was a staff attorney of the Cook County Legal Assistance Foundation from 1968 to 1970.

[2] Carr was a United States magistrate judge of the United States District Court for the Northern District of Ohio in 1979, becoming the first full-time magistrate judge in Toledo.

On May 19, 2002, Chief Justice William Rehnquist appointed Carr to the Foreign Intelligence Surveillance Court.

Carr served as chief judge of the District Court from December 21, 2004 to June 1, 2010.

[2][4] In April 2017, Carr ruled that Ohio could not fine railroad companies for blocking roads.