The American commitment to free speech is the most robust in the world. But these days that tolerance stops at the border.

Two cases pending in federal court in Manhattan will soon test how far the government can go in keeping Americans safe from what a State Department manual calls the “irresponsible expressions of opinion by prominent aliens.”

One case concerns a decision by the Bush administration to bar a Muslim scholar from visiting the United States. The other is a criminal prosecution of two Brooklyn businessmen for transmitting Hezbollah’s television station on their satellite service.

The government’s actions in these cases are reminiscent, civil liberties groups say, of another era. For about four decades that coincided roughly with the cold war, the United States routinely barred intellectuals and literary figures from visiting here based on their political views. Graham Greene, Gabriel García Márquez and Doris Lessing were all excluded.

There may be something to be said for avoiding face-to-face encounters with shaggy leftists — the cigarette smoke, for starters, and the jargon, and the complacent moral superiority. But in largely repealing the law on ideological exclusion in 1990, Congress seemed to suggest that Americans could be trusted to make those decisions for themselves.

The spirit of the old law, the McCarran-Walter Act, was revived after the Sept. 11 attacks. The USA Patriot Act of 2001, for instance, allowed the government to deny visas to people who had used their “position of prominence within any country to endorse or espouse terrorist activity.”

The government invoked that law in 2004 when it denied a work visa to Tariq Ramadan, a Swiss philosopher and Muslim intellectual. As a consequence, Professor Ramadan had to give up a teaching appointment at, in the words of The Guardian newspaper, “that hotbed of Muslim extremism, the University of Notre Dame in Indiana.”

In the three years preceding the denial, Professor Ramadan had visited the United States 24 times, lecturing at Dartmouth, Harvard and Princeton — and the State Department.

Three academic and literary groups sued the government last year over the denial, saying they had a First Amendment right to hear from Professor Ramadan. “There is something so dangerous in keeping writers out of the country because they don’t support the government,” said Francine Prose, the president of the PEN American Center, one of the plaintiffs. “Tariq Ramadan is the voice of reason, of logic, of toleration and common sense.”

After the suit was filed, the government changed its rationale for excluding Professor Ramadan, now saying that he had contributed about $1,300 to a charity in Switzerland from 1998 to 2002. That charity, later designated a terrorist organization by the Treasury Department, in turn made contributions to Hamas, which had already been designated one. Professor Ramadan’s second-hand contribution amounted to material support for terrorism, the government said.

Excluding Professor Ramadan “in no way restricts speech,” government lawyers wrote in a brief in the case in May. He remains free to say what he likes, they continued, and Americans remain free to hear what he has to say. Just not in person in the United States.

Judge Paul A. Crotty — a federal district judge in Manhattan who was New York City’s chief lawyer under Mayor Rudolph W. Giuliani — will hold a hearing in the case on Thursday. In an earlier decision, he said the principles at stake were crucial ones.

“The First Amendment includes not only a right to speak, but also a right to receive information and ideas,” Judge Crotty wrote last year. That includes a right, he continued, quoting a Supreme Court decision, “to have an alien enter and to hear him explain and seek to defend his views.”

Lawyers for the defendants in the television case, Javed Iqbal and Saleh Elahwal, say the case against them, similarly, is “nothing less than a full frontal assault on the fundamental values inscribed in the First Amendment.” The men are charged with providing material support to Hezbollah, the radical Islamic Shiite group in Lebanon, by making its television station, Al Manar, available in the United States.

In a brief filed in July, the government said, in an echo of the Ramadan case, that the satellite case was only about business dealings and “has nothing to do with speech, expression or advocacy,” adding that “the defendants remain free to speak out in favor of Hezbollah and its political objectives.” But they may not transmit Al Manar’s message.

Copyright © 2007 Adam Liptak/The New York Times. All rights reserved.