Alienage Definition: Federal Jurisdiction and Equal Protection

In U.S. law, the alienage definition is straightforward: alienage is the legal status of being a person who is not a citizen or national of the United States. The Immigration and Nationality Act sets that baseline, and it sweeps in everyone from a tourist on a two-week visa to a lawful permanent resident who has lived in the country for forty years.¹ What makes the status worth understanding is not the definition itself but what follows from it: which court can hear your civil lawsuit, how much protection the Constitution gives you against discriminatory state laws, and how the IRS taxes your income.

Who Counts as an Alien

The classification is binary. You either hold U.S. citizenship or nationality, or you don’t, and if you don’t, you’re an alien for purposes of federal immigration law. Visa type, length of stay, and manner of entry don’t change that. A green card holder is still an alien in legal terms until they naturalize. So is an undocumented person who crossed the border last month and a student on an F-1 visa halfway through a degree.

Starting in 2021, federal agencies began replacing “alien” with “noncitizen” in public communications and internal guidance. The statutes themselves still use “alien,” so you’ll see both terms in government paperwork and court filings. They refer to the same underlying status.

Alienage Jurisdiction in Federal Court

One of the most concrete consequences of alienage is access to federal court. Under 28 U.S.C. § 1332(a)(2), a federal district court can hear a civil lawsuit between a citizen of a U.S. state and a citizen or subject of a foreign country, provided the amount in dispute exceeds $75,000 (not counting interest and court costs).² The rationale is old and practical: a foreign national litigating in an unfamiliar legal system deserves a neutral federal forum rather than a state court that might favor the local party.

Two features limit the doctrine. The damages claim must genuinely clear $75,000; courts generally accept the plaintiff’s stated amount unless the defendant can show to a legal certainty that it falls short. And a lawful permanent resident who is domiciled in the same state as the opposing party cannot invoke alienage jurisdiction. Congress carved out that exception because a green card holder living in the same state as the other side isn’t really the “outsider” the statute was designed to protect.²

Corporations get a layered treatment. A corporation is a citizen of every place it is incorporated and of the state or foreign country where it has its principal place of business.² A foreign corporation headquartered in Delaware holds both citizenships at once, and it has to satisfy the jurisdictional rules for both.

Equal Protection and State Laws That Target Non-Citizens

The constitutional consequences of alienage are where the doctrine gets its bite. In Graham v. Richardson (1971), the Supreme Court held that alienage is an “inherently suspect” classification, on the same constitutional tier as race and national origin. Non-citizens, the Court reasoned, are a “discrete and insular minority” who need heightened judicial protection.³

That means strict scrutiny. A state law that treats non-citizens worse than citizens must be narrowly designed to serve a truly compelling government interest, and most laws fail. In Graham itself, the Court struck down state laws conditioning welfare benefits on citizenship, holding that conserving state resources for citizens wasn’t a strong enough justification.³

The Political Function Exception

Not every alienage distinction triggers strict scrutiny. In Sugarman v. Dougall (1973), the Supreme Court struck down New York’s blanket ban on non-citizens in the competitive civil service but left room for states to require citizenship in positions where officials “participate directly in the formulation, execution, or review of broad public policy.”⁴ That carve-out became the political function exception.

Later decisions upheld citizenship requirements for police officers, on the theory that policing involves broad discretionary governmental authority, and for public school teachers, based on their role in shaping civic values.⁵ For jobs tied to core governmental functions, courts apply the far more permissive rational-basis test, which most laws easily pass.

Federal Law Is Reviewed Differently

The most counterintuitive feature of alienage doctrine is that Congress gets far more leeway than the states. In Mathews v. Diaz (1976), the Supreme Court held that Congress has broad authority to treat citizens and non-citizens differently in federal programs, and even to draw lines between different groups of non-citizens. Managing immigration and foreign relations is federal work, and the Court gives it wide deference.⁶

The result is a two-track system. A state restricting welfare benefits to citizens faces strict scrutiny and will almost certainly lose. Congress imposing an identical restriction on a federal benefit faces only narrow review and will almost certainly survive. Before evaluating any alienage-based rule, check whether it comes from a state legislature or from Congress. That single question often decides the case.

Undocumented Immigrants Are Still “Persons”

Equal protection reaches even those without lawful status. In Plyler v. Doe (1982), the Supreme Court struck down a Texas law that denied public education funding for undocumented children, holding that the Fourteenth Amendment’s equal-protection guarantee applies to every person within a state’s jurisdiction.⁷ Anyone subject to a state’s laws is a “person” for constitutional purposes, regardless of immigration status. That doesn’t give undocumented individuals the same rights as citizens in every setting, but states cannot categorically strip them of basic constitutional protections.

Alienage in the Tax Code

The IRS runs its own classification system, and it doesn’t line up neatly with immigration categories. For tax purposes you are either a resident alien, taxed on worldwide income like a U.S. citizen, or a nonresident alien, generally taxed only on U.S.-source income and filing Form 1040-NR.⁸

You qualify as a resident alien if you pass either of two tests:⁹

The green card test. If you hold a lawful permanent resident card at any point during the calendar year, you’re a resident alien. The status continues until you surrender the card, USCIS revokes it, or a federal court terminates it.¹⁰
The substantial presence test. Without a green card, you become a resident alien if you’re physically present at least 31 days during the current year and at least 183 days over a three-year weighted period. The formula counts all days in the current year, one-third of the days in the prior year, and one-sixth of the days two years back.¹¹

Some categories are exempt from the substantial presence count. Foreign students on F-1 visas don’t count their days for the first five years, and teachers or trainees on J-1 visas don’t count them for two out of their first six years in the country.¹¹

It’s also possible to be both a nonresident and a resident within a single tax year. That commonly happens the year someone arrives in or leaves the United States, and the IRS handles it through dual-status taxpayer rules.⁹

1
Office of the Law Revision Counsel. 8 USC 1101 – Definitions
2
Office of the Law Revision Counsel. 28 USC 1332 – Diversity of Citizenship; Amount in Controversy; Costs
3
Justia. Graham v. Richardson, 403 U.S. 365 (1971)
4
Justia. Sugarman v. Dougall, 413 U.S. 634 (1973)
5
Legal Information Institute. Alienage Classification
6
Justia. Mathews v. Diaz, 426 U.S. 67 (1976)
7
Justia. Plyler v. Doe, 457 U.S. 202 (1982)
8
Internal Revenue Service. About Form 1040-NR, U.S. Nonresident Alien Income Tax Return
9
Internal Revenue Service. Determining an Individual’s Tax Residency Status
10
Internal Revenue Service. U.S. Tax Residency – Green Card Test
11
Internal Revenue Service. Substantial Presence Test