She then served as an Assistant United States Attorney for the Eastern District of Kentucky, from 1987 to 1990.

She was appointed United States Attorney for the Eastern District of Kentucky in 1991, by President George H. W. Bush, and served in that capacity until 1993, when she entered private practice.

One of the firms Caldwell worked for was Dinsmore & Shohl, where she was made partner at their Louisville office.

[1] Caldwell also temporarily returned to teaching, serving as an adjunct professor at her alma mater, Transylvania University, during the 2000 school year.

A Courier Journal report on Caldwell's appointment as U.S. attorney in 1991 noted that she had dated senator Mitch McConnell.