He first worked as a trial attorney in the United States Department of Justice Environment and Natural Resources Division.

He was a partner at Freeborn & Peters LLP in Chicago, where he handled complex federal civil litigation.

In the fall terms of 1990 and 1991, while a teaching fellow at Harvard University, he taught a class on Greek mythology.

[3] He was nominated to the seat vacated by Judge David H. Coar, who assumed senior status on August 12, 2009.

[4] In July 2018, Lee, sitting by designation, wrote for the unanimous panel of the United States Court of Appeals for the Seventh Circuit in Doe No.

President Biden nominated Lee to the seat to be vacated by Judge Diane Wood, who announced her intent to assume senior status upon confirmation of a successor.