DETROIT — Gov. Gretchen Whitmer prevailed Thursday in a high-stakes challenge from Republican lawmakers who sued over her authority to declare emergencies and order sweeping restrictions during the coronavirus outbreak.

A 1945 law cited by Whitmer, a Democrat, is not limited to local and regional emergencies only and can have no end date, said Judge Cynthia Stephens of the Court of Claims.

The lawsuit by the House and Senate grew out of frustration with Whitmer’s one-size strategy to stop the spread of the coronavirus by keeping people at home statewide and shutting down businesses, even if some regions were not harmed much by the virus or COVID-19.

The Legislature did not extend Whitmer’s disaster emergency declaration in late April but she acted anyway, pointing to the ’45 law.

The Legislature preferred a 1976 statute that gives it a say in emergency declarations after 28 days. Indeed, the judge said the governor can’t use that law to extend emergencies without input from lawmakers.

The decision was a third time that a Court of Claims judge ruled in favor of Whitmer. The other lawsuits were brought by residents, a business owner and a new group that has organized protests at the Capitol.

Also, Whitmer has further relaxed stay-at-home restrictions, saying a ban on nonessential health procedures would be lifted next week and that groups of up to 10 people can gather immediately ahead of the Memorial Day weekend.

Retailers can reopen by appointment only, starting Tuesday, as long as there are no more than 10 customers inside at a time. People also can make an appointment to visit an auto dealer showroom. Social distancing requirements remain in place.

She said Thursday that the stay-home order, which remains in effect through May 28, will likely be extended.