In a 4-3 ruling, the justices rejected a lawsuit challenging an anti-gerrymandering ballot measure, meaning it will go to a statewide vote in November.
The constitutional amendment would entrust redistricting to an independent commission instead of the Legislature and governor.
It is a bid to stop partisan gerrymandering, the process of a political party drawing electoral maps to maintain or expand its hold on power. Michigan Republicans controlled redistricting after the 2010 and 2000 censuses.
They have nine of Michigan's 14 U.S. House districts and hold 27-10 and 63-46 majorities in the state Senate and state House, respectively.
The lawsuit was filed by a business-backed group that contended the ballot measure was too broad and that such changes instead would have to be decided at a rarely held constitutional convention.
But a majority of the high court — which is controlled 5-2 by GOP nominees or appointees — ruled that the Voters Not Politicians ballot committee's constitutional amendment is permissible because it would "not significantly alter or abolish the form or structure of our government, making it tantamount to creating a new constitution." They affirmed a state appeals court decision.
Under the initiative, a commission of citizens who meet certain qualifications would handle redistricting. There would be four Democrats, four Republicans and five members with no affiliation with either major party. The panel would be prohibited from providing a "disproportionate advantage" to a political party, using "accepted measures of partisan fairness."
An Associated Press statistical analysis of the 2016 election results found that Michigan's state House districts had one of the largest Republican tilts in the nation, trailing only South Dakota's. The AP used an "efficiency gap" analysis to measure potential gerrymandering — the same statistical tool later cited in a lawsuit that alleges Michigan's legislative districts are unconstitutional.
A separate statistical analysis conducted for the AP by the Princeton University Gerrymandering Project found that the extreme Republican advantages in some states were unlikely to be a fluke. The Princeton analysis found that the Republican edge in Michigan's state House districts had only a 1-in-16,000 probability of occurring by chance.
Voters in other states also will weigh in on redistricting this fall.
In Colorado, two proposed constitutional amendments have been placed on the November ballot by the Legislature. Petitions submitted in Missouri and Utah are awaiting certification.
Associated Press writer David A. Lieb in Jefferson City, Missouri, contributed to this report.