The ruling came down Friday afternoon from District Judge Michael Martinez in Denver.

Read Injunction Against Dougco Schools

The American Civil Liberties Union -- along with concerned parents -- had filed a lawsuit in late June seeking an injunction to stop the program.

Opponents argued the program amounted to government sponsorship of religion because vouchers can be used at more than a dozen religious schools.

School choice advocates had argued the government is not sponsoring a religion because the voucher checks go to parents, who are the ones who choose which school their children attend, including non-religious schools.

In March, the school board approved the Choice Scholarship Program that would provide a public stipend for up to 500 current Douglas County students to attend private school this fall. The qualified students would receive $4,575 vouchers to attend one of 19 public or parochial schools next school year. Fourteen of those schools are partnered with religious institutions.

In June, the American Civil Liberties Union, the parents group Taxpayers for Public Schools and others filed suits in Denver District Court against the district and the state board, challenging the legality of the voucher program, claiming it violates the Colorado Constitution's religious liberty provisions, which bar the use of public funds for religious schools.

More than 200 of the 500 students approved for the program had already received initial funding. It is not immediately clear what will happen to them.

"Parents have the right to choose private religious school for their children. They don't have the right to do it with public tax payer money." Said Mark Silverstein of the Colorado ACLU.

It is anticipated that Douglas County will appeal Friday's ruling.