In 1980, the American Psychiatric Association added “Gender Identity Disorder” to its third volume of the Diagnostic and Statistical Manual (DSM). Affecting approximately 0.014 percent of transgender persons, gender identity ­disorder or gender dysphoria is defined by the DSM as persistent cross-gender identification coupled with clinically significant distress in social, occupational or other important areas in functioning.

Common complications of the disorder include depression, emotional distress, isolation and suicide. Although the number of transgender persons in the United States is difficult to measure, data compiled by the UCLA School of Law's Williams Institute, estimates that 1.4 million adults in the United States identify as transgender—meaning that as many as 20,000 Americans are struggling with gender identity disorder, and likely many more who do not report or self identify as transgender.

Despite its place in the DSM, gender identity disorder was historically exempt as a “disability” under the Americans with Disabilities Act (ADA). The ADA explicitly exempts from its definition of disability “transvestism, transsexualism, pedophilia, exhibitionism, voyeurism, gender identity disorders not resulting from physical ­impairments or other sexual behavior disorders.” Remarkably, lawmakers at the time felt that allowing gender identity disorders to be protected under the ADA would result in protection for employees engaging in activities employers deemed to be “immoral.” However, in a less Neanderthal approach to gender identity, the U.S. District Court for the Eastern District of Pennsylvania rejected an employer's motion to dismiss holding that, after being refused accommodation for gender identity disorder, a transgender employee sufficiently stated a claim under the ADA, see Blatt v. Cabela's Retail, No. 5:14-cv-04822 (E.D. Pa. May 17).