Mary Jane Theis

Mary Jane Theis
Chief Justice of the Illinois Supreme Court
In office
October 26, 2022 – October 26, 2025
Preceded byAnne M. Burke
Succeeded byP. Scott Neville Jr.
Justice of the Illinois Supreme Court
In office
October 26, 2010 – January 29, 2026
Preceded byThomas Fitzgerald
Succeeded bySanjay Tailor
Personal details
BornMary Jane Wendt
(1949-02-27) February 27, 1949
Chicago, Illinois, U.S.
PartyDemocratic
SpouseJohn Theis
RelativesKen Wendt (father)
EducationLoyola University Chicago (BA)
University of San Francisco (JD)

Mary Jane Theis (born February 27, 1949) is a former justice of the Illinois Supreme Court for the First Judicial District in Cook County. In 2022, she became chief justice after the retirement of then-chief justice Anne M. Burke. Theis announced on January 12th, 2026, that she would resign from the Illinois Supreme Court effective January 29, 2026.