The Indiana voucher program, passed by the state Legislature in 2011, is the most sweeping in the nation.

The Indiana Supreme Court on March 26 upheld the nation’s broadest school voucher program in a ruling that supporters say could set a national precedent as other states look to build or expand programs that use public money to allow students to attend private schools.

Critics of the controversial ruling were quick to point out that it applies only to Indiana schools, however, and that the question is far from decided in other states.

Indiana’s highest court unanimously upheld a 2011 law providing vouchers for low- and middle-income families and cleared the way for an expansion being debated in the Indiana Statehouse. But more importantly, it could settle the case law for other states where school voucher programs face legal challenges, supporters contend.

“I think it will be incredibly influential,” said Bert Gall, senior attorney for the Washington, D.C.-based Institute for Justice, a libertarian organization. Gall helped defend the Indiana law.

The Indiana school voucher program, passed by the state Legislature in 2011, is the most sweeping in the nation and the biggest test yet of the controversial, conservative Republican idea that giving families choice creates a greater incentive for public schools to improve.

Unlike school voucher programs in other states, which are limited to poor families and failing school districts, the Indiana program is open to a much broader range of people, including parents with household incomes of up to nearly $64,000 for a family of four.

Jeff Reed, a spokesman for the Friedman Foundation for Educational Choice, said 530,000 Indiana students qualify for vouchers, although only 9,000 currently receive them. Public school officials fear the eventual loss of thousands of students, especially those from the middle class—along with the state money that comes with them.

The Milwaukee Parental Choice Program is the nation’s largest in terms of actual enrollment. That program, enacted in 1990, had 24,027 participants this school year, Reed said.

But there is evidence to suggest that vouchers have not led to improved student achievement in Milwaukee’s schools.

(Next page: What a large-scale study of the effects of vouchers in Milwaukee found)