School choice advocates suffered a bitter defeat Thursday, when Kentucky’s Supreme Court struck down a state law that allowed donors to receive tax credits for supporting private school tuition.

In its unanimous decision, the high court said the 2021 measure violated the state’s constitution as the justices upheld a lower court ruling issued more than a year ago.

The law’s opponents objected to using the state tax code to aid private education. The measure’s supporters said tax credits didn’t amount to government spending, even if they decrease revenues.

The measure was narrowly passed by the Republican-dominated legislature over Democratic Gov. Andy Beshear’s veto. It created a form of scholarship tax credits — referred to by supporters as “education opportunity accounts.” Under the measure, private donors backing the accounts would be eligible for tax credits.

The Supreme Court ultimately found that the formula violated the constitution.

“We are compelled to agree that the EOA Act violates the plain language of Section 184” of the state constitution, Deputy Chief Justice Lisabeth T. Hughes said in writing for the court. “Simply stated, it puts the Commonwealth in the business of raising “sum(s) . . . for education other than in common schools.”