The Trump administration on Tuesday will urge 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.

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The case will require the 2nd U.S. Circuit Court of Appeals to decide 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.

The Trump administration’s involvement in the lawsuit is one of several moves it has made that has alarmed LGBTQ groups. Last month, President Donald Trump signed a memorandum directing the U.S. military not to accept transgender men and women as recruits.

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During the Obama administration, the Justice Department had not weighed in on the case. But the U.S. Equal Employment Opportunity Commission (EEOC), which enforces Title VII, has been arguing for five years that bias against gay workers violates the law. So far, only one federal appeals court has agreed.

The EEOC will appear at Tuesday’s hearing on behalf of Zarda’s estate. Zarda died in a BASE-jumping accident after filing his lawsuit.

Related: Justice Dept. Files Brief Rejecting LGBTQ Workplace Protections

LGBTQ 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 separate case by a former hospital security guard in Georgia who says she was harassed because she is gay.

In June, dozens of companies, including Alphabet Inc’s Google, Microsoft and CBS Corp, submitted a friend-of-the-court brief asking the 2nd Circuit to rule in favor of Zarda’s estate.

Related: Court: Discrimination Against Gay Workers Not Prohibited

A three-judge 2nd Circuit panel in April had dismissed the case, citing a prior ruling that said discrimination against gay workers is not a form of sex bias.

The full court, which can overturn the prior decision, agreed in May to review the case. That came weeks after a Chicago-based appeals court became the first to rule that Title VII protects gay workers.

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

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