An Equal Employment Opportunity Commission (EEOC) opinion handed down Friday says transgender Americans are protected by Title VII of the Civil Rights Act of 1964.

The 5-member bipartisan commission unanimously agreed that employment discrimination based on a person's gender identity violates Title VII's prohibition on sex discrimination.

According to gay weekly Metro Weekly, the opinion was issued in response to a legal challenge filed by Mia Macy, a transgender woman who alleges she was turned down for a job at the Bureau of Alcohol, Tobacco, Firearms and Explosives after she informed the agency that she was in the process of transitioning.

“[T]he Commission hereby clarifies that claims of discrimination based on transgender status, also refereed to as claims of discrimination based on gender identity, are cognizable under Title VII's sex discrimination prohibition …,” the EEOC opinion reads.

Gay rights groups called the decision a game-changer for transgender rights.

“This ruling marks a sea change in the treatment of transgender people under federal law. After years of being wrongly and unfairly excluded from federal protections against sex discrimination, transgender workers will now enjoy the same protections against unlawful discrimination based on gender stereotyping as other Americans. Mia Macy and the Transgender Law Center deserve enormous credit for bringing this historic case, which has resulted in a landmark ruling that will change the lives of countless transgender people,” Kate Kendell, executive director of the National Center for Lesbian Rights (NCLR), said in a statement.

The San Francisco-based Transgender Law Center is representing Macy in her lawsuit.

“With so many barriers to gainful employment in our society, we can't let discrimination be one of them,” Masen Davis, executive director of the Transgender Law Center, said in a statement. “The EEOC's decision ensures that every transgender person in the United States will have legal recourse when faced with employment discrimination. Having the protection of federal law is especially critical for transgender people who live in the 34 states that lack transgender-inclusive nondiscrimination laws. This is a game changer for transgender Americans.”