Wisconsin’s Supreme Court on Wednesday rejected the extension of a stay-at-home order by Gov. Tony Evers, siding with Republicans in one of most high-profile challenges of its kind to the emergency authority of a statewide official during the coronavirus pandemic.

Mr. Evers, a Democrat, had extended the prohibition on most travel and operations of nonessential businesses until May 26.

But in a 4-to-3 ruling, the conservative-leaning court said that measure had exceeded the authority given to Wisconsin’s top health official under state law.

“An agency cannot confer on itself the power to dictate the lives of law-abiding individuals as comprehensively as the order does without reaching beyond the executive branch’s authority,” the justices wrote in the ruling.