A Maine Superior Court judge has upheld a 23-year-old state law that prohibits towns from paying for students to attend religious schools.

In a decision dated Sept. 30 and released Monday, Justice Robert E. Crowley ruled Maine’s tuition law is constitutional. The law allows towns without schools to pay for students to attend public or private institutions, but not religious schools.

The Institute for Justice, a Washington-based law firm, filed the lawsuit two years ago on behalf of six families, saying the state’s refusal to pay for religious schools violated their right to free exercise of religion. Since then, two other families joined the suit.

All eight are from Minot, Durham or Raymond, towns that have no high schools.

For years, Maine has successfully argued that the U.S. Constitution forces it to exclude religious schools from its tuition programs. But two years ago, the U.S. Supreme Court ruled that the Constitution did allow a Cleveland voucher program to pay for children to attend church-run schools. That ruling opened the door for states to pay religious school tuition.

The Institute for Justice pointed to the Cleveland case in recent suit brought by the eight area families. Institute lawyers believed Maine could no longer say the Constitution forced it to exclude religious schools.

The Maine attorney general’s office, however, argued that the Cleveland case allowed states to pay for religious schools but did not require them to. Deputy Attorney General Paul Stern said Maine has the option to pay for religious schools, but has chosen not to.

He also argued that Maine’s public education system works best when it is diverse, not separate and sectarian. Maintaining that diversity, he said, is in the best interest of the state.

The judge agreed.

Both sides said they weren’t surprised by the ruling.

“From the beginning, we knew we’d probably be going to the Maine Supreme Court for this,” said Institute for Justice attorney Richard Komer.

Komer said his clients will “almost certainly” appeal the decision.

Currently, more than 6,100 Maine students receive public funds to attend schools outside their towns, not including those who need special education programs. Fifty-four Maine towns or townships have no school, while 90 have no high school.

The state has set a per-pupil tuition rate of $6,600, but towns can negotiate with schools for lower rates.

Six of the families involved in the suit send their teenagers to St. Dominic Regional High School in Auburn. One family sends its child to a public school. The eighth family home-schools its child.