A federal district court in Pennsylvania heard arguments last week in the first-ever case to challenge the transgender exclusion in the Americans with Disabilities Act (ADA).

The ADA’s passage in 1990 marked an extension of civil rights protections, prohibiting for the first time discrimination on the basis of disability. Congress has amended the law several times, but without taking out a portion of the original act that excludes from protection “transvestism, transsexualism, pedophilia, exhibitionism, voyeurism, gender identity disorders not resulting from physical impairments, or other sexual behavior disorders.”

Kate Lynn Blatt was hired as a seasonal stocker at Cabela’s Retail in the fall of 2006, according to allegations in the complaint. Before starting her job, she attended a two-day orientation dressed in female attire, and used the women’s employee restroom without issue. Once she started working, however, Blatt was prohibited from using the women’s restroom and was forced to wear a name tag depicting her name as “James,” even after she presented the director of human resources with documentation of her legal name change.

Blatt claims her colleagues called her “ladyboy,” “freak,” and “sinner.” Cabela’s made Blatt use the single-sex “family” restroom at the front of the store, rather than the female employee restroom closer to her work area, according to the complaint. Blatt claims she endured harassment from management and coworkers, and was abruptly terminated in March 2007.

Blatt sued, arguing Cabela’s discriminated against her based on her sex in violation Title VII of the Civil Rights Act of 1964, and that Cabela’s refused to reasonably accommodate Blatt’s formal diagnosis of gender dysphoria when the store denied her use of an appropriate restroom and the ability to wear a name tag with her correct name.

“Blatt’s case presents a critical issue … on the question of the constitutionality of the exclusion of transgender people from the ADA,” Jennifer Levi, Transgender Rights Project director at Gay & Lesbian Advocates & Defenders (GLAD), said in a statement. Levi is providing ongoing consultation in the case.

The Obama administration weighed in on Blatt’s case. In a statement filed with the court and in support of Blatt’s claims, the U.S. Department of Justice said that transgender people should be able to pursue ADA claims “because a growing body of scientific evidence suggests” that being transgender may have a physical origin.

LGBTQ organizations had previously criticized the Obama administration for ducking the issue of the transgender exclusion in the ADA, especially as the administration more aggressively pursued transgender employment discrimination claims under Title VII.

The court heard arguments on Cabela’s motion to dismiss Blatt’s claims, but did not immediately rule on Cabela’s request.