Nativism, the idea that government must guard native-born Americans from various threats posed by immigrants, has a long history in the United States.

Today, the Trump administration is citing the Immigration and Nationality Act of 1952, a restrictive measure written by nativist members of Congress decades ago when fears of communism were rampant, to sharply restrict the rights of noncitizens.

Under this law, also known as the McCarran-Walter Act, federal agencies have arrested and detained noncitizens associated with pro-Palestinian protests, reintroduced immigrant registration requirements, and imposed a new travel ban that affects 19 nations.

Since the 1950s, Congress has removed some of this sprawling federal law’s most discriminatory features, such as racist national origins quotas. But other key provisions remain on the books. Now they are the primary legal basis for some of President Donald Trump’s most controversial immigration crackdowns.

Foreign policy trumps free speech

In March 2025, the White House invoked the McCarran-Walter Act to justify arresting and deporting Mahmoud Khalil, a legal permanent resident who had participated in pro-Palestinian protests at Columbia University. Officials pointed to Section 237(a)(4)(C) of the law, which states that any “alien whose presence or activities in the United States the Secretary of State has reasonable ground to believe would have potentially serious adverse foreign policy consequences for the United States is deportable.”

This has been tried only once before. In 1995, the Clinton administration unsuccessfully sought to use the provision to deport a former Mexican official, Mario Ruiz Massieu, to face charges in his homeland for extortion and obstructing a murder investigation. Ruiz Massieu was later indicted in the U.S. on money laundering charges and died by suicide shortly before his arraignment.

The Trump administration cited the same provision to justify detaining Tufts University doctoral student Rumeysa Ozturk in March. Ozturk came under government scrutiny because she co-authored an op-ed in the Tufts student newspaper criticizing the university’s position on the Israel-Gaza war.

Surveillance footage of a terrified Ozturk being arrested by masked Immigration Customs and Enforcement agents on a street in Somerville, Massachusetts, drew criticism from government officials and civil liberties advocates. In response, Secretary of State Marco Rubio alleged that Ozturk had harmed U.S. interests by supporting “movements that are involved in doing things like vandalizing universities, harassing students, taking over buildings, creating a ruckus.”

Khalil and Ozturk both were released after weeks in detention, pending final resolution of their cases. Their lawyers argue that their clients’ treatment violates free speech protections and that the defendants were punished for expressing their political beliefs.

Monitoring noncitizens

The McCarran-Walter Act also authorizes intrusive registration and tracking requirements for noncitizens who remain in the U.S. for 30 days or longer.

On Jan. 20, 2025, Trump issued an executive order directing the Department of Homeland Security to enforce an “alien registration requirement.” The agency issued a final rule in April requiring all noncitizens over the age of 14 to register and be fingerprinted. Parents or guardians must register noncitizen children under age 14. The rule also requires adult noncitizens to carry “evidence of registration” at all times.

Such policies aren’t new. Noncitizen registration was codified in the Alien Registration Act of 1940, on the eve of U.S. entry into World War II. The law was designed to regulate the foreign-born population and encourage eligible noncitizens to join the U.S. armed forces. Its requirements were written into the McCarran-Walter Act.

After the 9/11 terrorist attacks, the Bush administration created the National Security Entry-Exit Registration System, which targeted noncitizen males age 16 or older from 25 Muslim-majority countries. It required registrants to submit biometric information, check in regularly with immigration authorities and use specific ports of entry for travel.

The Obama administration suspended this system in 2011 and permanently dismantled it in 2016.

Today, Trump administration officials say they are simply enforcing long-standing legal authority. A federal judge agreed, ruling on April 10 that the Homeland Security Department could require noncitizens to register and carry documentation.

Travel bans redux

On June 2, Trump announced a new travel ban on foreign nationals from 12 countries, mostly in Africa and the Middle East. The ban draws its authority from the McCarran-Walter Act. Two days later, Trump claimed the same legal discretion to exclude Harvard University’s international students from the U.S.

During his first term, Trump invoked these sections of the law to justify a travel ban on seven predominantly Muslim countries. The U.S. Supreme Court ultimately upheld this action in 2018 by a 5-4 vote in Trump v. Hawaii. Writing for the majority, Chief Justice John Roberts stated that the travel ban was well within broad powers over immigration granted to the president under the McCarran-Walter Act. He added that the court had “no view on the soundness of the policy.”

Trump’s new ban is more carefully crafted than earlier versions and more likely to withstand legal challenges. But his efforts to use the McCarren-Walter Act to ban international students from attending Harvard University face stiff legal headwinds.

On May 22, Homeland Security Secretary Kristi Noem notified Harvard officials that the agency was revoking the school’s certification to participate in the Student and Exchange Visitor Program, which grants visas to international students to come to the U.S. In a June 4 proclamation, the White House claimed that foreign students at Harvard had behaved in ways that threatened U.S. national security.

A federal judge in Boston quickly blocked the revocation, holding that it violated core constitutional free speech rights. “The government’s misplaced efforts to control a reputable academic institution and squelch diverse viewpoints seemingly because they are, in some instances, opposed to this administration’s own views, threaten these rights,” wrote Judge Allison D. Burroughs.

The latest step came on July 9, when the Trump administration subpoenaed Harvard for information on its foreign students, including their disciplinary records and involvement in campus protests.

Broad power over noncitizens

Ironically, congressional sponsors of the McCarran-Walter Act were at odds with the White House when the law was enacted in 1952. They overrode a veto by President Harry S. Truman, who thought the law’s nativist ideas were unfitting for a nation of immigrants and global defender of democracy.

However, the expansive executive powers created by this law have endured largely unaltered over time, through waves of immigration reform.

Now they are a boon to the Trump administration’s ambitious immigration crackdown. It’s a telling reminder that repressive old laws can come back to life – even when they don’t reflect the current views of many Americans.

Daniel Tichenor does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.