The petitioner does not contend that the stop-time rule itself suffers from any infirmity. Hampton v. Mow Sun Wong 96 S.Ct. However, the broad power to control immigration does not imbue Congress with plenary power over aliens themselves. The language of the due process clause refers to 'persons,' not 'citizens,' and it is well established that aliens within the territory of the United States may invoke its protections. For example, an alien may not be punished criminally without the same process of law that would be due a citizen of the United States.
Aliens enjoy some constitutional protections, regardless of their status.
The question petitioner raises is whether the Fifth Amendment's Due Process Clause requires Congress to provide a rational basis for its decision when it sets exclusion criteria for aliens. The Due Process Clause of the Fifth Amendment applies to the federal government a version of equal protection largely similar to that which governs the states under the Fourteenth Amendment. The Court pointed out that due process does not always require of the federal government what equal protection would of the states, and noted that the federal government can enact legislation that would be invalid under the Fourteenth Amendment if enacted by a State, particularly if the legislation related to immigration. The Supreme Court has also recognized that the governmental power to exclude or expel aliens may restrict aliens' constitutional rights when the two come into direct conflict. Because of foreign policy considerations, the United States government has encouraged Nicaraguans and Cubans to remain in this country, and had also given special protections to other Central American and European groups.