Democrats in two Midwestern states won seats currently held by Republicans in Tuesday's elections, winning their first majority on Michigan's high court and taking a Republican seat on Ohio's court. In Illinois, the election results could open the door to a GOP majority in the next election.

Partisan interests and billionaires spent millions of dollars in these races. The election outcomes could impact cases involving COVID-19 and criminal justice, as well as lawsuits filed by injured consumers.

Michigan

Voters overwhelmingly re-elected Chief Justice Bridget McCormack, a Democrat who became chief with the support of GOP justices. And the voters narrowly chose Democratic lawyer Elizabeth Welch to fill a seat currently held by a retiring conservative Republican. As a result, the Michigan Supreme Court will consist of a 4-3 Democratic majority, the first in a decade.

The court's conservative majority recently struck down Gov. Gretchen Whitmer's executive orders banning nonessential activities during the COVID-19 pandemic; in a 4-3 party-line vote, it invalidated a law granting the governor broad powers to protect public safety. The decision was written by retiring Justice Stephen Markman, a conservative Republican who has been on the court since 1999 and who served as an early leader in the conservative Federalist Society.

For years, the Michigan Supreme Court has tended to rule for corporate defendants in lawsuits filed by injured workers or consumers. And in 2015, the conservative majority ruled that fees collected by public-employee unions were "taxes" under the state constitution, even though the fees went to a private organization. This year's Republican high-court candidates were backed by the Michigan Chamber of Commerce's political action committee, which spent $800,000 to help them.

McCormack and Welch benefited from millions of dollars in outside spending, far more than the Republicans, according to reports filed with the state. Much of the money came from a political action committee tied to lawyers who represent injured people.

In addition to the outside-spending edge, McCormack's larger margin of victory could be the result of an incumbency advantage in judicial elections. In states like Michigan, where candidates' party affiliations don't appear on the ballot, incumbents are almost always re-elected. Without the incumbency advantage, Republicans in Michigan have historically struggled to win elections for open seats.

Ohio

The state's voters sent former Secretary of State Jennifer Brunner, a Democrat who was elected to that post, to their high court. Brunner defeated Justice Judith French, a Republican who faced criticism for appearing at partisan events. GOP Justice Sharon Kennedy, however, was re-elected by a wide margin — both Brunner and Kennedy won by around 10 percentage points.

The results will narrow the court's GOP majority to 4-3. Before the 2018 election, the court was all-Republican, but Democrats won two seats that year.

This year, the two Republican incumbents spent more than $1 million on campaign ads, according to the Brennan Center for Justice. And they were backed by the Republican State Leadership Committee, which is funded by big business and dark-money groups. GOP political consultant Karl Rove, who has worked with the RSLC, issued a plea to raise funds for French.

Brunner's campaign claimed that the RSLC's attack ad included lies. She called on French and Kennedy to abide by their pledges to renounce misleading attacks — a pledge that Brunner declined to adopt. She raised more than $250,000, with half of that money coming from the state Democratic Party.

Democrats will have another chance to gain a majority on the court in the 2022 election, when two Republican justices will be on the ballot. If they do, the Republican-led Legislature could theoretically add two seats to the court in a lame-duck session, packing it to effectively undo the election results. Republicans in North Carolina floated the same idea in 2016, after voters elected a progressive majority, but didn't go forward.

Illinois

Justice Thomas Kilbride became the first Illinois Supreme Court justice to lose a retention election, in which voters decide whether to keep incumbent justices on the bench, after he was targeted by attack ads that tied him to a controversial Democratic politician. Billionaire Ken Griffen donated $2 million to a group that spent about the same amount of money on ads attacking Kilbride, and Kilbride's campaign spent $2.6 million on ads. Total spending for the race exceeded $11 million, according to The Chicago Tribune.

Kilbride received 55 percent of the vote, but he needed 60 percent to win the retention election. The seat held by Kilbride, a Democrat, will be filled in a partisan election in 2022, and control of the court will be up for grabs. In addition to ousting Kilbride, voters in another district elected a Republican justice to replace a retiring Republican.

Big-business groups also targeted Kilbride in his 2010 retention election, but he managed to hang on. At the time, Kilbride's retention election was the most expensive judicial race in the country. This year's race fell short of the new record, set in a 2015 Pennsylvania Supreme Court race.

Now that Kilbride has lost, the court itself will appoint someone to fill his seat for two years. It's unclear if Kilbride himself will participate in that decision, and if he doesn't, the court could split 3-3 along party lines.

Justices in Illinois are elected in districts, and Kilbride's district is in the northern part of the state, stretching from the Chicago suburbs to the border with Iowa. Most of the counties in the district are red, but Will County, just outside Chicago, accounts for around 40 percent of the population in the district.

This article has been updated to correct the spelling of Michigan Chief Justice Bridget McCormack's surname and to clarify that the victory by Elizabeth Welch in Michigan did not involve ousting an incumbent.