Our client Mahmoud Khalil is just the first victim of Trump’s unconstitutional crackdown

The Trump administration is sending a message to everyone in America: If you dare to disagree with the president, you will be punished.

That was clear when Immigration and Customs Enforcement agents illegally arrested and detained Mahmoud Khalil, a lawful permanent resident and recent graduate student at New York’s Columbia University, in retaliation for his advocacy for Palestinian human rights. The federal government separated Khalil from his wife, an American citizen, who is nine months pregnant, and shipped him from New York to New Jersey and then Louisiana. A judge recently ruled his case should be heard in New Jersey.

Mr. Khalil has never been accused, charged or convicted of any crime. He was ripped from his home, detained and threatened with deportation in retaliation for his political beliefs. His case represents a clear attempt by the Trump administration to silence dissent, intimidate our universities and attack our freedom.

Khalil is not the only target of this crackdown. Secretary of State Marco Rubio claims he’s revoked hundreds of visas of students and visitors for similar reasons.

If this administration is not reined in, the paper-thin legal theory it is using to justify detaining and deporting Mr. Khalil could be wielded to deport anyone who opposes Trump on any issue. That would embolden a president who is already laying siege to academic freedom, the free exchange of ideas and open debate. It would put everyone — citizen and noncitizen alike — in danger.

That’s why the New York Civil Liberties Union is representing Mr. Khalil in court, alongside our colleagues at the ACLU of New Jersey and the national ACLU (Mr. Khalil is also being represented by City University of New York’s CLEAR clinic, the Center for Constitutional Rights, Alina Das of Washington Square Legal Services, Van Der Hout LLP and Amy Greer of Dratel + Lewis).

Central to our case is the fact that the Constitution’s right to free speech covers everyone in the U.S., regardless of their citizenship status. The administration is trying to get around these protections by abusing a rarely used aspect of U.S. immigration law to punish protected speech.

Trump is relying on an obscure provision in the 1952 Immigration and Nationality Act that says the government may deport people if there are “reasonable grounds” to believe their presence in the country “would have potentially serious adverse foreign policy consequences for the United States.”

The provision was tested once before 30 years ago, when the U.S. government tried to deport a former assistant attorney general of Mexico, Mario Ruiz Massieu, who faced criminal charges in his home country. In that case, the late federal Judge Maryanne Trump Barry — Trump’s older sister — ruled the law was unconstitutional.

But unlike Massieu, Mr. Khalil is not accused of any crime. Instead, the government claims that all advocacy on behalf of Palestine and Palestinian people would have serious adverse foreign policy consequences. This is untrue and unconstitutional.

The Trump administration claims falsely that any criticism of Israel is antisemitic. Antisemitism is a very real and serious problem — and some in Trump’s orbit, including billionaire Elon Musk, have trafficked in it. What the president and his team are doing won’t curtail antisemitism, and doing so isn’t their real goal.

Instead, the federal government is attempting to weaponize false charges of antisemitism to vastly expand presidential power and launch the most extreme threat to free speech since the Red Scare nearly 80 years ago. During the Cold War, lawmakers and government officials stoked fear of Russia and the “Red Menace” to justify a witch hunt and purge the federal government, and every aspect of American life, of so-called communists. They abused their power to paint anyone who disagreed with them as a communist or communist sympathizer. U.S. officials revoked passports of prominent activists, denied dissidents’ visas and deported noncitizens whose ideas they didn’t like.

Sound familiar? In fact, the Immigration and Naturalization Act the administration is using to try to deport our clients is a relic of the Red Scare, and was used to deny entry to many European Jews. No matter what your views on Israel and Palestine are, none of us should be eager to return to that dark period in our nation’s history.

This Red Scare redux is playing out not just with individuals, but with universities across the country. Columbia University, where Mr. Khalil studied, recently capitulated to a slew of government demands including implementing a mask ban, giving dozens of campus officers new arrest powers and placing two departments under “academic receivership.” In exchange for its surrender of academic freedom, all Columbia got was the mere possibility that the Trump administration would restore $400 million in federal funding.

Columbia was just the first target. Harvard and Princeton are now in danger of similar treatment. This is a full-scale attack on the system of free inquiry, discussion and debate that is at the core of higher education, which is so crucial to the strength of our democracy.

None of us should want our country to be a place where our government deports people for their beliefs, whether on foreign policy or anything else. No one, not even the president, has the power to deport someone for saying something the government doesn’t like.

The Trump administration has put Mr. Khalil and the people he loves through immense pain, and he should be freed as soon as possible. Everyone who believes in democracy should stand up and speak out against this power grab and demand freedom for Mr. Khalil and too many others wrongfully abducted and detained in Trump’s deportation machine.