The Indiana Supreme Court may well surprise supporters of the state school voucher program that has been challenged on constitutional grounds, at least if the oral arguments in the case are truly suggestive. (You can listen for yourself by clicking here.)

Vouchers are a favorite tool for some school reformers, and the scope of the program in Indiana makes the outcome of this case important to follow. The lawsuit, Teresa Meredith, et al. v. Mitch Daniels, et al., is a constitutional challenge to the Indiana Choice Scholarship Program, which Gov. Mitch Daniels (R) signed into law on May 5, 2011, and which is open to middle- and lower-income families. Most voucher programs in the country have been aimed at lower-income families, but the Indiana program allows families earning as much as $107,920 to apply for voucher money. The program, now in its second year,  provides vouchers to 9,324 families signed up; last year it enrolled 3,919 families.

The plaintiffs are 12 Indiana residents who argue that the program violates the Indiana constitution in two ways: one, its directive that the state educate children through a “system of Common schools”; the other, its provision that residents not be compelled to pay through taxes to support religious institutions.

The justices’ questions indicated concern about the argument over taxpayer money going to fund religious institutions. The panel heard from program opponents that the public school system is losing resources to vouchers and that nearly all of the voucher money is being spent at religious schools. Solicitor General Thomas Fisher argued that the program did not violate the state constitution because the money was really going to parents who were deciding where to use the money. But Justice Stephen David asked what it would mean if nearly all Indiana students wound up taking voucher money and enrolling at religious schools.  “What if 97 percent of kids end up going to religious schools? That is altering the state of education,” he said.

The justices also asked why it was acceptable for taxpayer money to be used to pay for tuition at K-12 religious schools and not for  scholarships for Indiana students to attend religious-affiliated colleges and universities.

These questions raise enough issues that it seems possible that the court will decide that the voucher program is too broad. Stranger things have happened.  Remember U.S. Supreme Court Chief Justice John Roberts’s surprise decision to uphold uphold President Obama’s health care law earlier this year.