The American Civil Liberties Union is suing one of the biggest health care systems in the U.S. for denying transition-related coverage to transgender employees, according to an ACLU press release.The federal lawsuit was filed against Dignity Health on behalf of Josef Robinson, a transgender man who works as an operating room nurse at Chandler Regional Medical Center. Dignity refused to cover transition-related treatment—often referred to as gender dysphoria treatment—that was prescribed by Robinson's doctor. According to the ACLU, Robinson had to pay thousands of dollars out of pocket. He then filed a discrimination complaint with the Equal Employment Opportunity Commission, "which issued a determination finding reasonable cause to believe that the Dignity Health insurance plan discriminates against Robinson on the basis of sex and authorized him to sue the health system," the ACLU says.The lawsuit argues Dignity Health has a "discriminatory insurance policy" that "contradicts widely accepted medical standards and violates federal law," the press release says. The provider's refusal to cover medically necessary transition care discriminates on the basis of sex, violating even the Affordable Care Act, which prohibits discrimination based on sex, including gender identity, according to the National Center for Transgender Equality San Francisco-based Dignity Health operates 39 hospitals and more than 400 care centers in Arizona, California and Nevada. The lawsuit was filed in the U.S. District Court for the Northern District of California.