The vouchers have helped cover the cost of private school for foster children and disabled students. The justices ruled Wednesday that the programs run afoul of the Arizona Constitution's bans on using tax dollars to support private schools.

Lower courts had split on the issue.

Arizona's high court previously upheld another state effort to help defray the costs of private-school education. In 1999 it said an income tax credit for individuals making donations for private school scholarships was constitutional.