PHOENIX — Saying it’s really a legal contract between the state and parents, state schools superintendent John Huppenthal is urging the Arizona Supreme Court to uphold the legality of what amounts to a voucher program for students.

In legal papers filed late Friday, Huppenthal acknowledged the law, first approved in 2011, allows parents to use funds from the state to send their children to private and parochial schools. The aid equals 90 percent of what the state would otherwise pay in aid to send that child to a public school.

But Huppenthal disputed the contention of the Arizona Education Association and others that the program violates a state constitutional provision that bars aid to private or parochial schools. And he said the funds also do not violate a separate section of the constitution that forbids any public funds from being used for religious worship or instruction.

What the court rules will most immediately affect perhaps 100,000 youngsters who are eligible for what the Legislature has dubbed “Empowerment Scholarship Accounts.’’ These are available to students with special needs, and to any student in a school rated “D” or “F” by the state Board of Education.

But proponents of the plan have publicly acknowledged they want it expanded statewide. That could mean state funds for private or parochial education — or even home schooling — for the 1.1 million children now in public schools.

Prior efforts by lawmakers to provide such aid have been struck down as unconstitutional. The Arizona Supreme Court has said the state was effectively giving money to private and parochial schools, whether directly or through checks given to parents, which then had to be signed over to one of those schools.

Don Peters, representing the AEA, the Arizona School Boards Association and others, contends this latest plan to give money to parents is just as illegal.

In his argument to the high court, Peters said all this new version does is shift the money around in a different way. The bottom line, he said, is no matter how you look at it, public dollars wind up in the coffers of private and parochial schools.

But Huppenthal said the program “only indirectly benefits private schools.”

He said the program sends money to the Department of Education, which then contracts with parents of qualifying students. While the parents can spend the money at a private or parochial school, Huppenthal said, they do not have to spend it there. There are other options, including books and supplies for home schooling and tutors.

Earlier this year, the state Court of Appeals ruled it is the fact the parents decide where to spend the funds that makes the program constitutional.

The Supreme Court justices have yet to decide whether they will even review the appellate court ruling.