The Justice Department is throwing its support to three families suing Maine’s education commissioner, alleging he discriminated against them by not allowing public funds to be used for their children’s tuition at religious schools.

It was the Trump administration’s latest move in an effort to overturn state laws that prevent public money from being used for religious schooling, a stated goal of Education Secretary Betsy DeVos. Most states have similar laws, which are increasingly coming under legal attack in part because of President Trump’s 2017 executive order promoting “Free Speech and Religious Liberty.”

The case in Maine is Carson v. Makin, which was filed last year and takes aim at a 1981 state law restricting the use of public funds. That law was challenged more than a decade ago and was ruled constitutional by a federal court. But the Supreme Court has made recent moves suggesting it might strike down constitutional restraints on the use of public money for religious schools when such a case comes before it.

In Maine, some districts do not have a public high school for residents to attend. The state’s Town Tuitioning Program allows public money to be spent so those children can attend neighboring public or private secular schools.

The three families sued Maine Education Commissioner Robert Hasson, saying they had been discriminated against because of their exclusion from the program and that their constitutional rights invoked in the First and 14th Amendments — including rights to free speech and due process — had been violated.

The Justice Department filed a “statement of interest” in the case this week, supporting the families. The department has previously submitted amicus briefs in lawsuits aiming to overturn these laws, known as Blaine Amendments.

Last month, it filed a statement of interest in support of parents and religious high school students who sued the state of Vermont. They claimed that the state had violated their constitutional right to free exercise of religion by preventing the students — who attended religious school — from accessing a state program to pay for tuition for up to two college courses.

Last year, the Justice Department filed a statement of interest in Montana on the side of parents who claimed that their constitutional rights had been violated when the state barred them from participating in a private-school scholarship program for religious school tuition.

Two years ago, the Supreme Court ruled in Trinity Lutheran Church v. Comer that states could not exclude religious institutions from participating in state-funded programs if those programs have a secular intent.

The case involved a Missouri church that had sought funding from a state program to refurbish its preschool playground but was initially denied because the state constitution forbids financially supporting a religious institution. The church sued, and while the policy in the state was subsequently changed by a new governor, the case made it to the high court, where, by a 7-to-2 vote, the justices said the state’s original decision violated the U.S. Constitution’s protection of free exercise of religion.