2 SESSIONS v. MORALES-SANTANA Opinion of the Court physical-presence requirement. Opposing removal to the Dominican Republic, Morales-Santana asserts that the equal protection principle implicit in the Fifth Amend­ ment1 entitles him to citizenship stature. We hold that the gender line Congress drew is incompatible with the requirement that the Government accord to all persons “the equal protection of the laws.” Nevertheless, we can­ not convert §1409(c)’s exception for unwed mothers into the main rule displacing §1401(a)(7) (covering married couples) and §1409(a) (covering unwed fathers). We must therefore leave it to Congress to select, going forward, a physical-presence requirement (ten years, one year, or some other period) uniformly applicable to all children born abroad with one U. S.-citizen and one alien parent, wed or unwed. In the interim, the Government must ensure that the laws in question are administered in a manner free from gender-based discrimination. I A We first describe in greater detail the regime Congress constructed. The general rules for acquiring U. S. citizen­ ship are found in 8 U. S. C. §1401, the first section in Chapter 1 of Title III of the Immigration and Nationality Act (1952 Act or INA), §301, 66 Stat. 235–236. Section 1401 sets forth the INA’s rules for determining who “shall be nationals and citizens of the United States at birth” by —————— 1 As this case involves federal, not state, legislation, the applicable equality guarantee is not the Fourteenth Amendment’s explicit Equal Protection Clause, it is the guarantee implicit in the Fifth Amend­ ment’s Due Process Clause. See Weinberger v. Wiesenfeld, 420 U. S. 636, 638, n. 2 (1975) (“[W]hile the Fifth Amendment contains no equal protection clause, it does forbid discrimination that is so unjustifiable as to be violative of due process. This Court’s approach to Fifth Amendment equal protection claims has always been precisely the same as to equal protection claims under the Fourteenth Amendment.” (citations and internal quotation marks omitted; alteration in original)).