The United States Supreme Court has held that enactment of a male-only draft registration requirement does not violate the equal protection component of the fifth amendment due process clause.
Rostker v. Goldberg, 453 U.S. 57 (1981).
Michael B. Sedlock,
Constitutional Law - Fifth Amendment - Due Process - Equal Protection - Sex Discrimination,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol20/iss3/8