Washington -- In a few words caught on tape, Osama bin Laden pronounced himself guilty of masterminding the suicide attacks on the World Trade Center, legal experts said Thursday.
"We asked each of them to go to America [for] a martyrdom operation," Bin Laden said. "We calculated in advance the number . . . who would be killed based on the position of the tower."
While he says he expected that many workers would be killed on the upper floors of the trade center, the collapse of the two buildings was more than "we had hoped for," a chortling Bin Laden told his dinner companions.
Those words show that Bin Laden was behind the Sept. 11 attacks, said University of Houston law professor Jordan Paust. "He is talking about himself as the leader, or one of the leaders, who sent them here. It is a smoking gun as to his complicity.
"Under international criminal law, a leader or co-leader can be held responsible for the actions of those he directs," he said.
Prior to discovery of the tape, U.S. officials were convinced that Bin Laden was responsible for the attacks because he had declared a holy war against America. The wealthy Saudi exile had set up training camps in Afghanistan for young recruits whose mission was to "kill Americans."
The tape released Thursday not only confirms those suspicions but also shows Bin Laden explaining details of the "operation" that he had kept secret even from his close aides in Afghanistan.
"The brothers who conducted the operation . . . didn't know anything about" it, he said, except Mohamed Atta, who "was in charge of the group. . . . Those who were trained to fly didn't know the others."
Khaled Abou El Fadl, acting professor of Islamic law at UCLA law school, said he watched the tape on an Arabic channel Thursday and listened to the audio in Arabic.
"I teach law and terrorism, but I find this tape disturbing," he said. "At one point, they even mock the idea that innocent people died in the attack. If I were a judge or jury, I would weigh this heavily. Among his close associates, he is genuinely happy," El Fadl said of Bin Laden.
However, El Fadl said, "some experts on [Arab television network] Al Jazeera said they thought it was doctored. I don't think so. For the most part, it flows. There is a gap, maybe one word missing, and then the same subject continues. . . . The audio is pretty bad, but the Arabic is distinct."
Yale University law professor Ruth Wedgwood called the tape a damning piece of evidence against Bin Laden: "From the point of view of a prosecutor, I would say it is more than a slam dunk, it was a home run."
She pointed to the portions of tape where Bin Laden said that "we calculated" the number of casualties in advance and the floors that would be hit, and that he knew the date of the attacks five days in advance. Moreover, she cited Bin Laden's comment about how his "experience" told him the fire from the plane would melt the structure of the trade towers.
"This all shows advance knowledge and participation, if not direction, of the terrorist acts," said Wedgwood, a former federal prosecutor in New York. "Any claim that he is simply celebrating someone else's operation is put to rest by use of the collective noun 'we.' "
There is a distinct contrast between this tape and the tape released Oct. 7, the day U.S. bombing began, she said, adding, "Everything was in the passive voice on the first tape. Here, he uses the active voice."
The tape looked like "it was made as a souvenir for this visiting sheik. The camera often lingers on him. It's like this guy was star-struck and wanted his picture taken with the boss," she said.
The tape is incriminating not just for its words but "because of the visual image of Bin Laden gloating about one of the most horrifying events of our history," said Loyola law professor Laurie Levenson.
In an ordinary federal court, defense lawyers would try to exclude the tape as evidence by arguing that it was doctored or otherwise not reliable, several lawyers said.
New York lawyer Gerald Shargel, who represented mob boss John Gotti, said tapes do not always lead to guilty verdicts.
"There are two traditional ways to challenge a tape," he said. "You can argue the content doesn't establish your client's guilt. Or you can argue the tape is not authentic."
"If this tape is authentic, and it appears to be so, Bin Laden is cooked," Shargel said. "And besides that, no one realistically thinks he will end up in a civilian court."
If Bin Laden is captured alive, U.S. authorities plan to bring him before a military tribunal.
"There, the rules of evidence are relaxed," said Duke University law professor Scott L. Silliman, an expert on military law. "The general rule is that if the evidence is reasonably reliable, it is admitted."
In post-World War II military trial of Japanese Gen. Tomoyuki Yamashita, U.S. prosecutors used as evidence news clips describing Japanese atrocities, Silliman said, even though such information would not be used as evidence in an ordinary trial.
Besides condemning Bin Laden, the tape also provides damaging evidence against his top associates in the Al Qaeda network, said Brian O'Neill, a Santa Monica lawyer and former chief of special prosecutions in the U.S. attorney's office in Los Angeles. Legally, the tape "kills the person who is said to be associated with Bin Laden," he said.
"It is devastating. There is no other honest way to look at it," O'Neill said.
Consequently, experts said, defense lawyers would try to keep the tape out of the trial of Zacarias Moussaoui, the 33-year-old Frenchman of Moroccan descent who was indicted this week on conspiracy charges in the Sept. 11 attacks.
Two prominent Los Angeles defense lawyers, Gordon Greenberg and Howard Weitzman, said they thought there was a good chance that a judge would bar use of the inflammatory tape on the ground that it is inadmissible as hearsay.
Others disagreed, however. In any case involving the Sept. 11 attacks, "the odds are one in a thousand some judge will keep it out. Otherwise, no one in his neighborhood will talk to him again," O'Neill said.
But the tape also has potential benefits for Moussaoui.
"No one mentioned Moussaoui on the tape. He is not mentioned by the architect of the conspiracy, Bin Laden, who mentions other people," O'Neill said. "You couple that with the fact that Moussaoui was in jail at the time of the attacks."
Moreover, Bin Laden says Al Qaeda operatives in the U.S. were kept in the dark about the planned hijacking. Even those who were going on the suicide mission "didn't know anything about the operation," Bin Laden said, until "just before they boarded the planes."
If Moussaoui is convicted of conspiracy, his lawyers could argue that he does not deserve a death sentence because he was unaware of the deadly plot, some lawyers said.
But former federal prosecutor Lawrence Barcella said a jury is unlikely to look kindly on the Al Qaeda conspirators.
"He didn't come here to arrange a tea social," Barcella said. "They were sent here for a terrorist operation. Under the law, co-conspirators are fully responsible for all the acts of the conspirators.