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Mary Kay O'Brien
Justice, Illinois Supreme Court · 3rd District
Background: Her career experience includes working as an attorney (associate and later partner) at the law firm of Cortina, Mueller & O’Brien, and as a partner in the firm of O'Brien and Smith. O'Brien was elected to the Illinois House of Representatives in 1996 and served until December 2003.
At a glance
- Court
- Illinois Supreme Court
- Position / seat
- 3rd District
- Chief justice
- No
- How they joined the court
- Elected (first elected 1996)
- Appointed by
- Not applicable (elected)
- Appointment date
- Not applicable (elected)
- Took office
- December 5, 2022
- Current term ends
- December 6, 2032
- Next election or retention vote
- Not listed
- Last election
- November 8, 2022
- Party (as listed by Ballotpedia)
- Democratic
- Ballotpedia partisanship estimate
- Not listed
- Education
- Bachelor's: Western Illinois University
- Law: University of Illinois, 1993
- Prior offices
- Illinois 3rd District Appellate Court (2003 - 2022)
- Profession
- Attorney
- How this court's justices are chosen
- Partisan electionVoters elect the justices; candidates' party labels appear on the ballot.
Summary of facts listed on Mary Kay O'Brien’s Ballotpedia page (retrieved Oct 26, 2026) · Photo: Ballotpedia. “Not listed” means Ballotpedia didn’t list it in a form this site could read; check Ballotpedia for the latest.
No public decision data available for this court.