WARSAW — As Anders Behring Breivik has given shocking and remorseless accounts to a Norwegian court of how he massacred 77 people, his testimony has revived a debate about how much of a public platform mass murderers should be given in trials.
Such atrocities, after all, often are waged for attention and carried out in the name of political or religious goals, and a trial gives perpetrators more of what they crave: a huge audience.
In the worst case, there is a risk that Mr. Breivik's trial, during which he has raised a right-wing salute and gloated about his killing rampage, could spawn copycat crimes by others who share his hatred of Muslims.
"There is a contagion effect that one has to take into consideration," said Brigitte Nacos, a Columbia University professor who studies terrorism and the mass media.
Col. Zbigniew Muszynski, head of Poland's Counterterrorism Center, said security experts believe there already have been violent acts inspired by Mr. Breivik, including an Italian extremist's killing of two African immigrants in Florence late last year.
"There is always the potential danger that someone who hasn't been exposed to extremist propaganda could become interested in it and could undertake activity that is in violation of the law," Col. Muszynski said.
Democracies generally tend to give suspects in even the most horrific crimes the chance to speak out freely in court, though sometimes they place limits on what can be broadcast to a wider public.
When Serbian autocrat Slobodan Milosevic went on trial in The Hague on war crimes charges, he tried to use the court as a pulpit to defend policies that led to the Balkan wars of the 1990s and to rouse nationalists back home.
The court closed his sessions several times when his rhetoric reached fever pitch, though by then - with Milosevic's rivals holding power in Serbia - his words had little impact on the political situation in his homeland.
Peruvian courts silenced Abimael Guzman, the founder of the once-fearsome Shining Path guerrilla group, during a series of trials after his 1992 capture.
His sessions were held mostly behind closed doors, with journalists watching from a soundproof booth. Microphones were shut off during a 2004 trial, when he was given a chance to speak, and used it to declare: "Long live the Communist Party of Peru! Glory to Marxism-Leninism-Maoism! Glory to the Peruvian people!"
In Mr. Breivik's case, there is a strong sense among Norwegians that the public has a right to know as much as possible about the killing rampage.
The court has allowed reporters to cover the grisly details of Mr. Breivik's testimony. But it has also tried to deny him excessive publicity: Photos for the most part are allowed only at the start of sessions, and filming during his testimony has been mostly restricted.
Even so, some Europeans say their gut reaction is that it's too much coverage. They have been horrified by images splashed across newspapers of Mr. Breivik making a defiant fisted salute and reports of his bloodcurdling admission of his crimes.
"The trial should have been kept secret or at least behind closed doors, and the court should only issue a statement with the verdict," said Malgorzata Rogala, 50, a translator in Poland, where courts sometimes limit media coverage in sensitive cases. "It is an insult to the families of the victims and publicity he does not deserve."
But some legal scholars argue that true openness is essential, if only to prevent conspiracy theories. And public trials are a bedrock of democracy that specialists say must be allowed in most cases.
"The underlying human rights dimension of this is that public trials have a very central place in the consciousness of the community," said Mike Newton, a law professor at Vanderbilt University. "And so, the presumption should be an open trial unless there is clear evidence that what goes on in the courtroom is just an extension of hostilities."
Mr. Newton, co-author of "Enemy of the State: The Trial and Execution of Saddam Hussein," argues that Saddam's trial is a case where there indeed would have been a good argument for a closed trial because the deposed Iraqi dictator used his testimony - broadcast on Iraqi television - to encourage the ongoing insurgency.
Perhaps ironically, some extremists who carry out horrific attacks to make a political point reject the opportunity to speak out in court.
An example is Timothy McVeigh, who acted out of hatred for the U.S. government when he bombed a federal building in Oklahoma City in 1995, killing 168 people. Defense attorneys feared that if McVeigh testified, it would open him up to too many questions from prosecutors about his role in the bombing.
McVeigh's distrust of the government also might have played a role in his refusal to testify, but he later worked with a biographer to tell his side of the story, and he appeared to welcome the attention he got before he was executed in 2001.
"Timothy McVeigh got a lot of mail when he was on death row. Some people were supportive, and he even got marriage proposals," Columbia's Ms. Nacos said. "McVeigh died a happy man. He said he accomplished what he wanted."