One example is that transgender people are psychiatrically diagnosed with gender identity disorder. This disorder is characterized by “an intense and persistent self-identification as the opposite gender, combined with persistent discomfort with the assigned sex.” By receiving a diagnosis of a disorder, transgender people are perceived as mentally unstable and therefore excluded from society. This discrimination is evident in cases where transgender students have been excluded from school for wearing clothing deemed inappropriate for their biological sex. Other cases of transgender discrimination concern "difficulty in accessing social services because their gender identity and expression were different from the gender documented on their birth certificate, driving license, passport and other official documents", as in the case by Avery. Furthermore, in cases where transgender people wanted to undergo sex reassignment surgery, they were required to accept a diagnosis of mental illness regardless of their emotional stability and psychological health. They also “reported discrimination and cultural insensitivity in substance abuse treatment programs, including verbal and physical abuse by staff, requirements that they dress according to their biological gender, and