We cannot allow all of these people to invade our Country. When somebody comes in, we must immediately, with no Judges or Court Cases, bring them back from where they came. Our system is a mockery to good immigration policy and Law and Order. Most children come without parents...— Donald J. Trump (@realDonaldTrump) June 24, 2018
Zadvydas v. Davis, 533 U.S. 678 (2001), at 693-694.
The distinction between an alien who has effected an entry into the United States and one who has never entered runs throughout immigration law. See Kaplan v. Tod, 267 U. S. 228, 230 (1925) (despite nine years' presence in the United States, an "excluded" alien "was still in theory of law at the boundary line and had gained no foothold in the United States"); Leng May Ma v. Barber, 357 U. S. 185, 188-190 (1958) (alien "paroled" into the United States pending admissibility had not effected an "entry"). It is well established that certain constitutional protections available to persons inside the United States are unavailable to aliens outside of our geographic borders. See United States v. VerdugoUrquidez, 494 U. S. 259, 269 (1990) (Fifth Amendment's protections do not extend to aliens outside the territorial boundaries); Johnson v. Eisentrager, 339 U. S. 763, 784 (1950) (same). But once an alien enters the country, the legal circumstance changes, for the Due Process Clause applies to all "persons" within the United States, including aliens, whether their presence here is lawful, unlawful, temporary, or permanent. See Plyler v. Doe, 457 U. S. 202, 210 (1982); Mathews v. Diaz, 426 U. S. 67, 77 (1976); Kwong Hai Ghew v. Golding, 344 U. S. 590, 596-598, and n. 5 (1953); Yick Wo v. Hopkins, 118 U. S. 356, 369 (1886); cf. Mezei, supra, at 212 ("[A]liens who have once passed through our gates, even illegally, may be expelled only after proceedings conforming to traditional standards of fairness encompassed in due process of law"). Indeed, this Court has held that the Due Process Clause protects an alien subject to a final order of deportation, see Wong Wing v. United States, 163 U. S. 228, 238 (1896), though the nature of that protection may vary depending upon status and circumstance, see Landon v. Plasencia, 459 U. S. 21, 32-34 (1982); Johnson, supra, at 770.