A series of decisions by the Obama administration loosened the legal concept of sex in federal programs, including in education and health care, recognizing sex largely as an individual’s choice — and prompting fights over bathrooms, dormitories, single-sex programs and other arenas where gender was once seen as a simple concept. Conservatives, especially evangelical Christians, were incensed.

Now the Department of Health and Human Services is spearheading an effort to establish a legal definition of sex under Title IX, the federal civil rights law that bans gender discrimination in education programs that receive government financial assistance, according to a memo obtained by The New York Times.

The department argued in its memo that key government agencies needed to adopt an explicit and uniform definition of gender as determined “on a biological basis that is clear, grounded in science, objective and administrable.” The agency’s proposed definition would define sex as either male or female, unchangeable, and determined by the genitals that a person is born with, according to a draft reviewed by The Times. Any dispute about one’s sex would have to be clarified using genetic testing.