FILE - SCOTUS Justice-nominee Brett Kavanaugh

Justice Brett M. Kavanaugh

The U.S. Supreme Court on Wednesday heard oral arguments in a Montana school choice case that could directly impact 37 state constitutions banning public funds from being used on religious schools.

During the arguments, the court's conservative justices seemed ready to strike down at least some state restrictions banning all public funds from being used on religious schools.

The case in question, Espinoza v. Montana Department of Revenue, is considered by many to be a landmark religious liberty and school choice case dating back to 19th century law, which many argue is unconstitutional because it requires governments to prohibit public funding from being directed toward religious schools.

Montana was among many western states to adopt such an amendment after Congress stipulated in 1875 that doing so was a pre-condition of joining the Union. Montana joined the Union in 1889 after delegates to the 1889 Montana constitutional convention passed the Blaine Amendment to the state constitution.

In 2015, Montana launched a program that provides tax credits to individuals and businesses that donate to private schools. The donations then are used as financial aid for parents who can't afford to send their children to private schools but want to.

Shortly after the program was launched, the state barred any of the money from going to religious schools, citing the Blaine Amendment. But three families filed suit, challenging the decision.

The Montana Supreme Court eventually ruled the entire program was unconstitutional and struck it down. The decision was appealed the U.S. Supreme Court, which agreed to hear the case.

Conservative justices on Wednesday questioned whether the decision was discriminatory.

"What if the state said you can use scholarship funds for private schools, but not for Jewish or Protestant schools? Wouldn't that be discrimination?" Justice Brett Kavanaugh asked.

The Michigan-based Mackinac Center for Public Policy was one of several groups across the country to file an amicus brief in support of the parents who challenged the ban.

"The case offers the Supreme Court the opportunity to reject anti-aid, or Blaine, amendments," the Mackinac Center said in a news release. "This could remove the remaining major legal obstacle to universal educational choice in many states, including Michigan."

Patrick Hughes, president and co-founder of the Liberty Justice Center, which also supports the parents, said that "families have a constitutional right to choose a school for their children that reinforces their values and beliefs rather than undermining them. The First Amendment is a stalwart against rogue moves like that of Montana. The state is using the First Amendment to discriminate instead of protect, and the Supreme Court must uphold the rights of Americans of all religions to participate in school choice.”

The Supreme Court is expected to rule on the case by the end of its term in June.