WASHINGTON (NEXSTAR) — The U.S. Supreme Court ruled it illegal to fire someone from their job for being gay or transgender on Monday.

Alsphonso David, president of the Human Rights Campaign, says the ruling has huge implications for millions of LGBT Americans living in areas without existing protections.

“This decision is a landmark victory for LGBTQ people across the country,” David said. “Now people can be protected by federal law and have the comfort of knowing the Supreme Court has issued a momentous decision.”

The ruling was 6 to 3.

“I can’t underscore how significant it is. We all, in most cases, have to work,” David said.

Conservatives Chief Justice John Roberts and Associate Justice Neil Gorsuch sided with the liberal end of the court.

The crux of the legal fight came down to the word “sex.” Gorsuch wrote in his opinion that firing someone for their sexual orientation or gender identity is “undisguisable from their sex. Something Americans are already protected against.”

“This ruling is disappointing,” Kate Anderson with Alliance Defending Freedom said.

Anderson represented the Michigan funeral home that lost in Monday’s ruling.

“We’re talking about changing the meaning of sex and where we’ve seen that happen in other cases and other areas we’ve seen some significant issues for women,” Anderson said.

Aimee Stephens, one of the plaintiffs in the case, was fired from her job after transitioning, therefore violating her job’s dress code. She died last month.

Her fight marked the first transgender case to ever reach the supreme court.

Anderson hopes Congress takes action to better define the word.

Minority Leader Chuck Schumer is calling on Senate Republicans to pass the Equality Act to further expand protections for LGBT Americans.

“That would be the great leap forward on equality we’re all looking forward,” Schumer said.

That bill has been stalled in the Senate for more than a year.