In a split decision issued Thursday, the court struck down a portion of the law that deals with collective bargaining rights. But it affirmed the rest of a decision by a King County Superior Court judge.

"The remainder of the Charter School Act is constitutional on its face," said the lead opinion, written by Justice Mary Yu.

Washington state voters approved charter schools in 2012, after rejecting them three times. After the Supreme Court struck down that law, the Legislature acted in 2016 on a replacement law, which was at issue in this case.

Teacher unions and other groups, like El Centra de la Raza, sued in King County Superior Court over the new law.

The opponents argued that public money shouldn’t go to schools over which voters have no control – charters answer to unelected boards, not elected school boards. They said public schools were under-funder already, and that money was being diverted from them.