International instruments fail to specify the meaning of gender identity. Yet gender identity has been invoked as a prohibited ground of discrimination, particularly in cases concerning trans persons. Trans existences fall outside the expectation of a correspondence between sex and gender. “Trans” is an umbrella term referring to people who do not identify with the sex attributed to them at birth. This broad definition encompasses pre-operative and post-operative transsexuals, as well as persons who have not undergone any medical intervention and do not conform to the social norms of expression and self-identification imposing the binary. Regional conventions do not define the concept of gender identity either. Documents issued by the United Nations (UN) and regional human rights bodies frequently rely on the category, without any clear explanation of the notion, or of what makes gender identity different from gender as such. Relying on Lacanian psychoanalysis, this essay argues that gender is an identity per se and challenges international law's treatment of gender and gender identity as distinct categories. Underlying this essay is the view that questioning the shape that the law gives to “gender identity” is the preliminary step to evaluating what protections human rights law can or cannot offer to individuals.