Indiana joins states like Louisiana and Wisconsin, where voucher or voucher-style laws have been upheld. But Arizona and Florida's courts have ruled against vouchers, and the issue remains to be resolved in other states.
Supporters say the Indiana ruling could influence courts in other states because the Indiana constitution contains a clause copied by many states in the mid-1800s in an effort to bar public aid for Catholic schools. The so-called "Blaine Amendment" was meant at the time to keep public money flowing to Protestant-dominated public schools.
That means the Indiana ruling could apply anywhere with a "Blaine" law, Gall said.
"For us, and for the Indiana Supreme Court, the Blaine Amendment in Indiana basically prevented spending for the benefit of religious institutions. And the Indiana Supreme Court said 'No, this is spending for the benefit of parents and students,'" he said.
Opponents downplayed Tuesday's ruling. Brenda Pike, executive director of the Indiana State Teachers Association and a lead plaintiff in the case, said the group now considers vouchers settled law in Indiana. But, she added, Indiana's borders are where the ruling's impact ends.
"This was a specific Indiana constitutional law question," Pike said. "We went through the court system in Indiana, not any federal court system."
Lawyers for national groups who argued against the Indiana law deferred questions to ISTA on Tuesday.
Solicitor General Thomas Fisher, who defended the law before the state Supreme Court in November, told the justices then that parents were free to send their children to any school they wished, public or private, religious or not.
The court agreed with that, saying in a 22-page opinion written by Chief Justice Brent Dickson that the program primarily benefited parents, not schools, because it gave parents the choice in their children's education.