Immigration restrictionists sometimes claim that noncitizens have no rights under the Constitution, and that the US government is therefore free to deal with them in whatever way it wants. At least as a general rule, this claim is simply false.
Noncitizens undeniably have a wide range of rights under the Constitution. Indeed, within the borders of the United States, they have most of the same rights as citizens do, and longstanding Supreme Court precedent bans most state laws discriminating against noncitizens. There is little if any serious controversy among experts over this matter.

Noncitizens undeniably have a wide range of rights under the Constitution.”]
The more controversial issue is whether the Constitution provides any protection for noncitizens outside US borders, particularly in regard to immigration issues.

Rights That Protect Aliens and Citizens Alike

The First Amendment prevents the government from censoring noncitizens’ speech or suppressing the practice of their religion. The Fourth Amendment protects them against unreasonable searches and seizures. The Fifth Amendment ensures that noncitizens’ property can only be taken by the government for a public use, and only if just compensation is paid.
Should a noncitizen be charged with a crime, he has exactly the same Fifth and Sixth Amendment procedural rights as a citizen, including the right to a jury trial, the right to counsel, and protection against self-incrimination. If convicted, the Eighth Amendment prevents the government from subjecting aliens to “cruel and unusual punishment” in exactly the same ways as it does with citizens.

Rights Reserved to Citizens

The Constitution reserves a few rights for citizens alone. Most notably, the Privileges and Immunities Clause of Article IV, Section 2, and the Privileges or Immunities Clause of the Fourteenth Amendment both protect the “privileges” and “immunities” of US citizens against various types of interference by state governments.
The Second and Ninth Amendments indicate that the rights they protect are those of “the people.” While the Supreme Court has never addressed this issue, lower courts have disagreed over whether “the people” entitled to the Second Amendment right to keep and bear arms includes noncitizens, especially undocumented immigrants.
That a few constitutional rights may be specifically reserved to citizens underscores the broader principle that the vast majority are not. There would be no need to specify such a reservation if the Constitution had a default rule limiting rights to citizens.
In reality, the vast majority of rights outlined in the Constitution are phrased as general limitations on government power, not special protections for a specific class of people — be they citizens or some other group.

Constitutional Constraints on State Discrimination against Aliens

Not only does the Constitution grant noncitizens most of the same rights as citizens, but longstanding Supreme Court precedent also forbids many state laws discriminating against aliens. In cases such as Bernal v. Fainter (1984), the court has ruled that laws discriminating on the basis of alienage are subject to “strict scrutiny” — that is, they will be struck down unless the government can prove that they are “narrowly tailored” to the promotion of a “compelling state interest.”

Longstanding Supreme Court precedent also forbids many state laws discriminating against aliens.”]
Under that doctrine, courts have invalidated state laws excluding noncitizens from entering various professions, including becoming lawyers. Bernal, for example, struck down a Texas law preventing non-citizens from becoming notaries public. An important exception to the principle applies to laws excluding aliens from “political functions,” such as voting and holding elected office.
Some conservatives criticize court decisions restricting discrimination against aliens as left-liberal “judicial activism.” But such decisions have a substantial basis in the Fourteenth Amendment.
Representative John Bingham, one of the principal framers of the amendment, emphasized that one of the purposes of the amendment was to ensure “that all persons, whether citizens or strangers, within this land, shall have equal protection in every State in this Union in the rights of life and liberty and property.” While the framers were especially concerned with ending discrimination against African-Americans, they also sought to curb growing state discrimination against immigrants.
State governments are also forbidden to discriminate against immigrants based on national origin. In a recent high-profile decision, a federal court struck down an Indiana policy, enacted by then-governor Mike Pence, that denied state services to Syrian refugees that were made available to refugees from other nations.
The trial court ruled that this practice was “national origin” discrimination, forbidden by the Fourteenth Amendment. Its decision was later upheld by an appellate court panel that included prominent conservative judges Frank Easterbrook and Diane Sykes (the latter generally considered to be a likely future Republican nominee to the Supreme Court).

The Pernicious “Plenary Power” Doctrine

By far, the biggest exception to the courts’ generally favorable attitude toward extending constitutional rights to noncitizens is the so-called “plenary power” doctrine, which gives the federal government broad power to adopt otherwise unconstitutional policies in its treatment of aliens, when it comes to immigration policy.
Since the late 19th century, the doctrine has been understood as giving Congress very broad power to authorize the exclusion of aliens for almost any reason, including many rationales that would be forbidden in virtually any other context.
The plenary power doctrine has no basis in the text or original meaning of the Constitution. With a few exceptions noted above, none of the rights protected by the Constitution are textually limited to citizens. And none include a blanket exception for immigration cases.
The doctrine traces its roots to the highly racist and xenophobic era of the late 19th century. The animating ideology had a close connection to the judicial tolerance of Jim Crow segregation at home, which intensified around the same time. The origins of the plenary power doctrine lie not in the text of the Constitution but in the racial and ethnic prejudice of the same era that gave us Jim Crow and Plessy v. Ferguson.
Some argue that the plenary power doctrine is sound because aliens have no legal right to enter the United States in the first place; such admission is at the discretion of the US government. Whether the Constitution gives the federal government a general power to restrict immigration is debatable. But even if it does, it does not follow that this authority is exempt from the constitutional limitations that apply to every other exercise of federal government power.

Whether the Constitution gives the federal government a general power to restrict immigration is highly questionable.”]
For example,  few doubt that Congress has the power to give or withhold Social Security benefits. That does not mean it is free to discriminate on the basis of race or religion in doing so, or that it can withhold benefits from individuals who engage in speech critical of the government.
While would-be recipients have no legal right to Social Security benefits as such (at least none that Congress cannot take away), they do have a right to expect that the government will not allocate benefits in ways that violate constitutional constraints on its authority, including by engaging in prohibited discrimination. There is no good reason why federal power over immigration should be treated any differently.

The Future of Plenary Power

It is unlikely that the plenary power doctrine will be fully overturned in the near future. But, as leading immigration law scholars Peter Spiro and Adam Cox have explained, recent Supreme Court decisions suggest that it may not be as robust as it once was and that it might be subject to various constraints.
The reach of the plenary power doctrine is the main issue in the ongoing litigation over President Donald Trump’s “travel ban,” the executive order barring citizens of several Muslim majority countries from entering the United States. In any context other than immigration, Trump’s order would likely be dead in the water.
It was clearly motivated by a desire to discriminate against Muslims, as evidenced by Trump’s own statements and those of his advisers, as well as by its laughably weak  security rationale.  Discrimination on the basis of religion is clearly unconstitutional in nearly any other context. The initial order was also vulnerable because it forbade entry even to citizens of the affected countries who had preexisting visas or legal permanent resident status.
Legal challenges to the initial order won a series of victories in court that soon forced Trump to withdraw it and replace it with a somewhat less egregious version. But the new order  still reflects the discriminatory intent that animated the original and still has a security rationale so transparently weak as to make it implausible that discrimination was not its true purpose.
So far, two federal trial court decisions have ruled against the revised order, while another has ruled in its favor. The litigation will surely continue, perhaps all the way to the Supreme Court. Whatever ultimately happens, the litigation over the two travel ban orders has shown that the plenary power doctrine is not as firmly established as its most fervent defenders like to think.

The plenary power doctrine is not as firmly established as its most fervent defenders like to think.”]
Over time, perhaps courts will further rethink this indefensible exception to the principle that the rights protected by the Constitution are general limits on government power that protect citizens and noncitizens alike.
With a few exceptions noted above, none of the rights protected by the Constitution are limited to citizens. And none include a blanket exception for immigration cases.