In more than 90 minutes of arguments heard by teleconference due to the coronavirus pandemic, the justices struggled over how courts can determine when a religious entity must face an employee’s civil rights lawsuit and when it is immune because of protections previously recognized by the high court.

Conservative justices asked questions indicating support for shielding the schools from such litigation. Liberal justices seemed to lean toward the teachers. The court has a 5-4 conservative majority. President Donald Trump’s administration sided with the schools.

A ruling favoring of the Catholic schools could strip more than 300,000 lay teachers working in religious schools of employment law protections and could impact industries including nurses in Catholic hospitals, the plaintiffs said.

Teachers Agnes Morrissey-Berru and Kristen Biel accused the schools of firing them due to discrimination. Morrissey-Berru accused her school of age discrimination. Biel accused hers of discrimination based on disability stemming from breast cancer treatment. Biel died last year after a five-year battle with the disease.

At issue is the breadth of a “ministerial exception” that protects religious organizations from employee suits alleging violations of laws such as Title VII of the Civil Rights Act of 1964, which bars employers from discriminating against employees on grounds including sex, race, national origin and religion.

In a 2012 ruling, the Supreme Court recognized the ministerial exception under the U.S. Constitution’s First Amendment guarantee of religious freedom. The exception, meant to prevent government interference with religion, restricts discrimination lawsuits by certain employees if they hold a ministerial role.

The justices in that case left unresolved how to decide when an employee qualifies for this ministerial role, a thorny question that the justices struggled with on Monday.

Conservative Justice Clarence Thomas offered hypothetical examples such as a chemistry teacher who starts class with a “Hail Mary” prayer, a chemistry teacher who is also a nun and a lay teacher who teaches religion.

“I don’t see what standards a secular court would use to determine which of those is an important … religious duty or function,” Thomas said.

Liberal Justice Ruth Bader Ginsburg said she found it “very disturbing” if a person could be fired or refused a job for any reason “that has nothing to with religion.”

Morrissey-Berru sued Our Lady of Guadalupe School in Hermosa Beach after being told in 2015, just before her 65th birthday, that her contract would not be renewed. Biel sued St. James School in Torrance after she said she was dismissed when she requested time off to undergo surgery and chemotherapy for her cancer. Her husband has continued the litigation on her behalf.

Both private schools operate under the Roman Catholic Archdiocese of Los Angeles. Morrissey-Berru and Biel taught their students religion several days a week in addition to secular subjects.

Federal judges concluded that the ministerial exception barred both claims. The San Francisco-based 9th U.S. Circuit Court of Appeals subsequently ruled that both lawsuits could proceed.