BOISE, Idaho, April 23 - Not long after the terrorist attacks of Sept. 11, 2001, a group of Muslim students led by a Saudi Arabian doctoral candidate held a candlelight vigil in the small college town of Moscow, Idaho, and condemned the attacks as an affront to Islam.

Today, that graduate student, Sami Omar al-Hussayen, is on trial in a heavily guarded courtroom here, accused of plotting to aid and to maintain Islamic Web sites that promote jihad.

As a Web master to several Islamic organizations, Mr. Hussayen helped to maintain Internet sites with links to groups that praised suicide bombings in Chechnya and in Israel. But he himself does not hold those views, his lawyers said. His role was like that of a technical editor, they said, arguing that he could not be held criminally liable for what others wrote.

Civil libertarians say the case poses a landmark test of what people can do or whom they can associate with in the age of terror alerts. It is one of the few times anyone has been prosecuted under language in the antiterrorism law known as the USA Patriot Act, which makes it a crime to provide "expert guidance or assistance" to groups deemed terrorist.

"Somebody who fixes a fax machine that is owned by a group that may advocate terrorism could be liable," said David Cole, a Georgetown University law professor who argued against the expert guidance part of the antiterrorism law this year, in a case where it was struck down by a federal judge.

Mr. Hussayen, 34, a father of three who was pursuing a doctorate in computer sciences at the University of Idaho, is charged with three counts of conspiracy to support terrorism and 11 counts of visa and immigration fraud. His trial opened on April 14 and is expected to last until June.

The trial offers conflicting views of Mr. Hussayen, a son of the Saudi middle class. Defense lawyers have portrayed him as a loving family man who embraces Western values while holding to his Islamic faith; the prosecution team has presented him as a secret conspirator, aiding the cause of terrorism through his computer skills.

[In a ruling that bolstered Mr. Hussayen's case on Monday, Judge Edward J. Lodge of Federal District Court in Idaho would not let prosecutors show the jury a Web page that encourages suicide bombings. The judge said the government must prove that Mr. Hussayen created the page or endorsed its contents.]

Earlier this year, Judge Audrey B. Collins of the Federal District Court in Los Angeles, struck down a part of the antiterrorism law being used in this trial, ruling that it was overly broad and vague. But Judge Collins did not extend her ruling beyond the one case in California.

President Bush made several recent campaign-style stops on behalf of the antiterrorism law, saying it is an essential tool for law enforcement.

"The Patriot Act defends our liberty, is what it does, under the Constitution of the United States," Mr. Bush said in Buffalo on Tuesday.

Idaho, one of the most Republican states, has become an unlikely home of opposition to the act.

The state's senior senator, the Republican Larry E. Craig, and Representative C. L. Otter, also a Republican, have sponsored bills to amend the act, which they have called a threat to civil liberties.

Mr. Hussayen's lead lawyer, David Nevin, is best known for his defense in 1993 of Kevin Harris, who was involved in a standoff with government agents at a cabin in Ruby Ridge, Idaho, along with Randall C. Weaver. That case, in which Mr. Weaver's wife and teenage son were shot and killed by government agents, is a cause célebre among mainly right-leaning civil libertarians.

Some of Mr. Hussayen's supporters say they see a similar kind of government abuse in his trial.

"It's an illustration of how much power the government can bring against somebody," said John Dickinson, a retired professor of computer sciences who was Mr. Hussayen's doctoral adviser at the University of Idaho. "It should scare anybody."

Mr. Dickinson said he was interviewed by the F.B.I. for several hours after Mr. Hussayen's arrest in February 2003. "They kept saying his Ph.D. program was a front and that the person I knew was only the tip of this monstrous iceberg," he said. "But I've yet to hear one thing the government has said since then that has made me question his innocence."

Justice Department officials and prosecutors refused to comment on the broader implications of the case, citing the trial. But in court documents, the government makes a case that Mr. Hussayen funneled money to Islamic charities with terrorist ties and that he posted calls for jihad by different Saudi sheiks.

In the indictment, the government charged that Mr. Hussayen provided "computer advice and assistance, communications facilities, and financial instruments and services that assisted in the creation and maintenance of Internet Web sites and other Internet medium intended to recruit and raise funds for violent jihad, particularly in Palestine and Chechnya."

And they have argued that Mr. Hussayen's technical assistance, even if he did not share the beliefs of the groups he helped, were like providing a gun to an armed robber.

Most of the facts are not in dispute. Mr. Hussayen's lawyers said that he gave money to legitimate Islamic charities and that his Web site work was protected by the First Amendment. The Web sites he maintained also posted views opposing jihad, they said.

The government has argued that Mr. Hussayen, a Saudi citizen who is the son of a retired Saudi minister of education, does not have all the protections of an American citizen. They said he abused his privilege as a student by working for computer sites that advocate terror. His friends in the Idaho college town may have known one side of him, the prosecutor, Kim Lindquist, said in his opening remarks to the jury, but they seldom saw "the private face of extreme jihad."

The Saudi government is paying for the defense of Mr. Hussayen, his family said.

One of the charities that Mr. Hussayen supported, Islamic Assembly of North America, still operates out of Ann Arbor, Mich. On its Web site, the group says its mission is to promote the spread of Islam, and the group solicits money from the public. Mr. Nevin said the charity has never been classified as terrorist by the government.

But the government said the Michigan charity was one of the Web sites that "accommodated materials that advocated violence against the United States."

Both sides in this case are looking to appeals that will probably turn on the part of the antiterrorism law thrown out by Judge Collins in January.

In that case, the judge ruled on behalf of several humanitarian groups that wanted to provide support to the nonviolent arms of two organizations designated as terrorist in Turkey and Sri Lanka. Judge Collins wrote that "a woman who buys cookies at a bake sale outside her grocery store to support displaced Kurdish refugees to find new homes could be held liable" if the sale was sponsored by a group designated terrorist.

The American Civil Liberties Union, which is trying to overturn the antiterrorism law in court, tried to join the Idaho case but was rebuffed by Judge Lodge.

"We very much wanted to be involved in this case because it is by far the most radical prosecution we've seen under the Patriot Act," said Ann Beeson, associate legal director of the national A.C.L.U. "You shouldn't be held liable for what somebody else said. Under this theory, you could charge the electrician who services the wrong client."