The Justice Department on Friday issued a statement of interest in support of the Archdiocese of Indianapolis in its ongoing dispute with a former Catholic school teacher who alleges he was wrongfully terminated because he was in a same-sex marriage. The United States has a "substantial interest in religious liberty," the Justice Department says.

Joshua Payne-Elliott is suing the archdiocese, alleging that it illegally interfered with his contractual and employment relationship with Cathedral High School, causing Cathedral to terminate him.

But in its statement, the DOJ said that the First Amendment protects the right of the Roman Catholic Archdiocese of Indianapolis to interpret and apply Catholic doctrine.

It was not immediately clear how binding the DOJ's statement is, or what impact it will have on Payne-Elliott's suit.

“If the First Amendment’s Religion Clauses stand for anything, it is that secular courts cannot entangle themselves in questions of religious law,” United States Attorney Josh Minkler said.

Background:Vatican pauses decree revoking school's Catholic status for refusing to fire a gay teacher

From July:An Indiana Catholic school fired a gay teacher for same-sex marriage. Now, a settlement

Payne-Elliott filed his suit in Marion County in July, saying in a news release that he hoped "this case will put a stop to the targeting of LGBTQ employees and their families." He was one of the three gay, married Catholic school employees fired at the direction of the archdiocese.

Two guidance counselors were fired from Roncalli High School. Payne-Elliott's husband, Layton Payne-Elliott, is a teacher at Brebeuf Jesuit Preparatory School. The archdiocese stripped Brebeuf of its Catholic identity after it refused to fire Payne-Elliott, though the Vatican recently suspended that ruling pending an appeal from the school.

Officials with Cathedral said the archdiocese threatened to do the same if Joshua Payne-Elliott's employment continued.

But Indianapolis Archbishop Charles C. Thompson has maintained that the church is not targeting anyone.

Rather, Thompson said, the archdiocese has a right to set whatever rules it wants for its schools and employees, including that they must live according to Catholic Church doctrine. The archdiocese began requiring a morality clause in teacher, administrator and counselor contracts at some of its schools four years ago, and at all Catholic schools two years ago.

"Religious liberty, which is a hallmark of the U.S. constitution and has been tested in the U.S. Supreme Court, acknowledges that religious organizations may define what conduct is acceptable and contrary to the teachings of its religion, for its school leaders, guidance counselors, teachers and other ministers of faith," the archdiocese said.

A statement of interest is described in court documents as a statement that speaks to the interests of the United States in a pending suit. It is not a ruling.

“The First Amendment to the United States Constitution protects the right of religious institutions and people to decide what their beliefs are, to teach their faith, and to associate with others who share their faith,” Eric Dreiband, assistant attorney general for the civil rights division, said in a statement. “The First Amendment rightly protects the free exercise of religion.”

The statement of interest says the First Amendment prevents courts from impairing the constitutional rights of religious institutions. The former teacher’s lawsuit attempts to penalize the archdiocese for determining that schools within its diocese cannot employ teachers in public, same-sex marriages, and simultaneously identify as Catholic, the statement says.

Supreme Court precedent holds that the First Amendment protects the archdiocese’s right to this form of expressive association, and courts cannot interfere with that right, according to the news release.

The statement of interest also says that courts cannot second-guess how religious institutions interpret and apply their own religious laws. Supreme Court precedent holds that the First Amendment forbids courts from engaging in “quintessentially religious controversies.”

Instead, the statement of interest says, “the legitimacy of the Archdiocese’s decision as a matter of Catholic law” is committed exclusively “to the judgment of the Archdiocese.”

Follow Justin L. Mack on Twitter: @justinlmack.