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.

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.........

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