["Law & Society Review, Volume 55, Issue 4, Page 539-562, December 2021. ", "\nAbstract\nHealth care rights for transgender and/or nonbinary people have dramatically expanded in recent years, including in insurance coverage for the treatments and procedures they need. Yet, trans people themselves still identify health insurance problems as a top priority for research and policy change because of significant difficulties gaining and using coverage. Wrangling over coverage determinations happens through multiple types of interactions, bureaucratic, interpersonal, and medical. When these interactions become difficult, it is because key terms such as medical necessity are both powerful and indeterminate. This study examines how trans people and health care intermediaries navigate the health insurance process and contest the meaning of medical necessity in coverage determinations. These disputes constitute the ground‐level reality for instantiating health care rights to gender affirming care. Relying on analysis of contract language and 32 interviews with people who sought gender‐affirming care and allied professionals, we find that health insurance policy language, interpretation, and implementation often create disadvantages and barriers for trans people who attempt to access care. Our study highlights how the contested life of insurance policy terminology produces a reality for rights but also details the mechanisms through which insurance‐mediated care is a socially contested and negotiated process\n"]