A federal appeals court on Monday ruled that a 1964 civil rights law bans anti-gay workplace discrimination. The decision rebukes the Trump administration — which had argued against a gay worker in the case — and hands progressives a win in their strategy to protect LGBT employees with a drumbeat of lawsuits.

The dispute hinges on whether Title VII of the Civil Rights Act of 1964, which bans discrimination on the basis of sex, also bans workplace discrimination due to sexual orientation.

The Court of Appeals for the 2nd Circuit ruled Monday, “We now hold that sexual orientation discrimination constitutes a form of discrimination ‘because of . . . sex,’ in violation of Title VII.” In doing so, the court overruled a lower court — and a precedent from two previous court cases — and remanded the case to be litigated in light of their reading of Title VII.

The decision holds national implications due to its high tier in the judicial system, and because it’s seen as a litmus test of the Trump administration’s ability — or inability — to curb LGBT rights through court activism. The Justice Department had injected itself into the case even though it wasn’t a party to the lawsuit and doesn’t normally involve itself in private employment disputes.

The case was heard in New York City by all 13 judges in the 2nd Circuit, known as an en banc hearing, which leaves the Supreme Court as the only avenue for a potential appeal.

In reaching its decision Monday, the court pointed out that anti-gay discrimination would not exist "but for" a person's sex. That is to say, gays, lesbians, and bisexuals would not experience this type of unequal treatment had they been born a different gender, or were attracted to a different sex. Read more via Buzzfeed