Dickson also rejected school voucher opponents' claims that the state constitution requires a public school system, saying lawmakers have broad discretion in how children are educated.
State School Superintendent Glenda Ritz joined the lawsuit while campaigning last year but removed her name from the list of plaintiffs shortly after winning office.
"As State Superintendent, I will follow the court's ruling and faithfully administer Indiana's voucher program," she said in a statement. "However, I personally believe that public dollars should go to public schools, and I encourage Hoosiers to send that message to their representatives in the Statehouse."
There is still some question about how popular the vouchers are in Indiana. Voters elected Ritz over former Republican Schools Superintendent Tony Bennett, long the state's most visible supporter of vouchers. But they also awarded a supermajority to House Republicans, who have pushed for a sweeping expansion of vouchers this year.
The expansion bill is awaiting action in the state Senate, where there have been concerns about its cost and whether the Legislature should start making exceptions to the 2011 compromise that then-Gov. Mitch Daniels touted as giving public schools a chance to win over students and parents.