INDIANAPOLIS (AP) — Indiana Supreme Court justices weighing the legality of the nation’s largest school voucher program made clear during a packed hearing Wednesday that the program’s fate may rest on whether it primarily benefits students’ parents or the religious institutions that run private schools.

The five justices prodded lawyers for both sides on the vouchers’ consequences as they heard a constitutional challenge to the 2011 law under which more than 9,000 students have switched from public to private schools with help from state funds. The program was pushed by Gov. Mitch Daniels and is considered a model of conservative Republicans’ approach to overhauling education.