The Equal Protection and Due Process clauses in Section 1 of the Fourteenth Amendment to the U.S. Constitution are ratified:
No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
While the scope of these protections has been slow to expand, they have served as the basis for many federal civil rights statutes, such as Title VII of the Civil Rights Act of 1964 and Title IX of the Education Amendments of 1972, which protect against discrimination "on the basis of sex" in education and employment contexts.
In December 1975, Minneapolis adopted an ordinance barring discrimination on the basis of “having or projecting a self-image not associated with one’s biological maleness or one’s biological femaleness,” becoming the first state to do so.