142 U.S. 651 (1892)
Nishimura Ekiu v. United States is a foundational Supreme Court decision that anchors the federal government's plenary power over immigration—especially the power to exclude noncitizens at the threshold of entry—and the corresponding limits on judicial review.
Whether Congress may conclusively entrust to executive immigration officers the determination of an arriving alien's admissibility—specifically, whether the alien is likely to become a public charge—and whether such an administrative determination precludes judicial reexamination of the facts on habeas corpus.
Congress possesses plenary power to regulate the admission and exclusion of aliens as an incident of national sovereignty. In exercising that power, Congress may commit to executive officers the authority to determine facts upon which exclusion depends, and it may make those factual determinations final and conclusive. Judicial review on habeas corpus is limited to inquiring whether the executive officer acted within the bounds of statutory authority and followed the procedures prescribed by Congress; courts may not reweigh evidence or conduct a de novo judicial trial of admissibility for arriving aliens. Administrative determinations made pursuant to valid statute constitute due process of law for would-be entrants at the border.
The Supreme Court affirmed the denial of habeas relief. The immigration officer's determination—made under authority delegated by Congress in the Immigration Act of 1891—that Ekiu was likely to become a public charge was final and conclusive on questions of fact, and the limited process provided by the statute constituted due process for an arriving alien seeking entry.
Nishimura Ekiu is a cornerstone of immigration and constitutional law. It entrenches the plenary power doctrine, endorses administrative finality in exclusion decisions, and constrains judicial review to narrow habeas inquiries about statutory authority rather than factual correctness. The case inaugurates the modern separation between the rights of arriving aliens and those within the country, later developed in cases distinguishing exclusion from deportation. It also informs contemporary debates about expedited removal and limited habeas review, serving as a historical antecedent for decisions that restrict judicial reexamination of administrative immigration determinations.