Michigan voters could keep Republicans in the majority on the state Supreme Court or shift control to candidates nominated by the Democratic Party.
Three seats on the seven-member court are at stake Tuesday. Republicans now hold a 4-3 advantage.
Supreme Court races have been expensive and contentious with insurers and other business groups supporting conservatives, and unions and trial lawyers backing liberal candidates.
Republican Justice Brian Zahra is being challenged by Democratic Detroit-area Judge Shelia Johnson and a third-party candidate.
In the other race, Republican Justice Stephen Markman is running for re-election. Voters can choose two candidates among five. The two with the most votes win.
Oakland County Judge Colleen O'Brien is the other GOP nominee. Democrats put up law professor Bridget McCormack and Wayne County Judge Connie Kelley.