Education advocates say Arizona is failing to fully fund its K-12 system for the coming budget year in violation of the state Constitution.
A victory before the state Supreme Court could mean the Legislature must find an additional $61 million at a time when many are predicting ongoing shortfalls.
The case revolves around a long- running debate over the language of an education-funding law that voters approved a decade ago.
An attorney for education groups suing the state said if state lawmakers want to do funding differently, they must go back to the voters.
The lawsuit alleges that by funding only part of the voter mandate, lawmakers violated the state Constitution, which prevents changes to a voter referendum unless the changes advance the cause of the referendum.