(Reuters) - A Trump administration lawyer on Tuesday urged a U.S. appeals court in Manhattan to rule that federal law does not ban discrimination against gay employees.

The U.S. Department of Justice is supporting a New York skydiving company, Altitude Express Inc, in a lawsuit brought by former instructor Donald Zarda, who accused the company of firing him after he told a customer he was gay and she complained. Zarda died in a BASE-jumping accident after filing the lawsuit, and his estate took over the case.

Judges on the 2nd U.S. Circuit Court of Appeals focused their questions on whether discrimination against gay workers is a form of unlawful sex bias under Title VII of the Civil Rights Act of 1964. That law bans discrimination based on workers’ sex, race, religion and other traits.

Justice Department lawyer Hashim Mooppan told the court that Congress never intended for that law to protect gay workers against bias. And in recent years, he said, lawmakers have repeatedly declined to pass bills that would prohibit employment discrimination against gay workers.

During the Obama administration, the Justice Department had not weighed in on the case. But the Equal Employment Opportunity Commission, which appeared at Tuesday’s hearing on behalf of Zarda’s estate, has been arguing for five years that bias against gay workers violates the law. The EEOC is an independent federal agency that enforces Title VII.

So far, only one federal appeals court, in Chicago, has agreed with the commission.

Several 2nd Circuit judges questioned Mooppan about why the Justice Department got involved, and whether it first consulted with the EEOC. Mooppan said it would not be appropriate for him to discuss the department’s internal procedures.

Lawyers for Zarda’s estate and the EEOC told the court gay workers are protected by Title VII because sexual orientation is necessarily linked to a person’s sex.

LGBT groups say the case is crucial because a victory for Zarda’s estate would deepen a split among federal appeals courts and increase the chances that the U.S. Supreme Court will take up the issue.

Earlier this month, the high court was asked to review a ruling that dismissed a similar case by a former hospital security guard in Georgia.

A three-judge 2nd Circuit panel in April had ruled against Zarda’s estate, citing a prior ruling that said discrimination against gay workers is not a form of sex bias. The full court can overturn the prior decision.

The case is Zarda v. Altitude Express Inc, 2nd U.S. Circuit Court of Appeals, No. 15-3775.