A District Court judge has ruled that a transgender woman can sue her former employer for sex discrimination under the Americans with Disabilities Act, even though the ADA expressly excludes transgender people from protection.

Kate Lynn Blatt claims she was fired from hunting and camping retailer Cabela's in 2007, after suffering prolonged harassment that included being denied access to the women's restroom and being forced to wear a name tag with her male birth name.

She is the first trans person to successfully file a suit citing the ADA.

Being transgender is not considered a disability under the ADA, which was signed into law 1991, nor is it designated a disorder by the American Psychiatric Association. But it can give rise to gender dysphoria, and it was on those grounds—as well as Title VII of the Civil Rights Act of 1964 against sex discrimination in employment—that Blatt's lawyers succeeded on making their case.

"I'm hopeful we will be able to expand civil rights for transgender people just a little," said attorney Neelima Vanguri.

She had hoped Judge Joseph Leeson would declare the ADA's standard that "transsexualism" does not qualify as a disability was unconstitutional. Instead he pointed to Blatt's gender dysphoria as a legitimate condition, allowing her case to proceed.

"The ruling is historic and important, adding to the momentum we’ve seen over the past several years for transgender people in court," said LGBT rights group Freedom for All Americans in a statement. "It lays a vital foundation for transgender people to pursue broad civil rights protections across many spheres of life, including employment and public accommodations."