WASHINGTON (AP) — Big companies are pushing back against proposed federal rules they say would require their medical plans to cover gender transition and other services under the nondiscrimination mandate of President Barack Obama’s health care law.

Civil rights advocates representing transgender people say the regulation, now being finalized by the Health and Human Services Department, would be a major step forward for a marginalized community beginning to gain acceptance as celebrities like Caitlyn Jenner tell their stories.

The issue mixes rapidly changing social mores and subtle interpretations of complex federal laws, including the Affordable Care Act. Obama has been recognized as the first president openly supportive of transgender rights.

The latest dispute over the health care law may have to be resolved by the courts. The law’s nondiscrimination section applies federal civil rights protections to programs under the health overhaul. The legal text refers to entities “receiving federal financial assistance,” interpreted to include insurers, state Medicaid agencies, hospitals and other service providers. It doesn’t mention major private employers that run their own health plans.

A group representing big employers said its members don’t have particular qualms about gender transition. But large employers do object to what they see as an overreach by the Obama administration, since their health plans don’t get federal financial assistance.

There’s nothing in the health law “that says ‘large employers, you are subject to this’,” said Gretchen Young, health policy vice president for the ERISA Industry Committee. “People are getting concerned there will be a whole body of things that will come up in the future.” Another concern: that a bar against discrimination on account of nationality could mean having to provide translation in up to 15 languages.

ERISA is a 1970s federal law that governs big-employer benefit plans. Employers design their own plans and set aside money to cover the expected medical costs of their workforces. They usually hire an insurance company as a “third-party administrator” to handle claims and run the day-to-day operations.

That’s where the connection to the health law’s nondiscrimination rule comes in.