The potential for Abu Hamza’s speeches to cause “damage” was “simply incalculable”, the British judge sentencing the cleric said today.
Mr Justice Hughes told the preacher that his words had created a “real danger” for people across the world.
They generated an atmosphere in which his devoted followers felt it was their duty to kill.
He also commended suicide bombing and specifically encouraged the assassination of foreign leaders.
Mr Justice Hughes said he did not “make the mistake” of thinking that Hamza represented Islamic thinking generally.
But he said it was “perfectly plain” that Hamza had spoken with “considerable authority”.
His audiences had trusted him to tell them “what their Islamic duty was”, he said.
“You spoke with great anger, it was directed at virtually every country and a very large number of people,” the judge added.
He continued: “You are entitled to your views and in this country you are entitled to express them – up to the point where you incite murder or incite racial hatred
“That, however, is what you did. You used your authority to legitimise anger and to encourage your audiences to believe that it gave rise to a duty to murder.
“You commended suicide bombing, you encouraged them to kill in the cause you set out for them.”
In addition to preaching to his audiences, “thousands more” had heard his words because the speeches were distributed on video tape, the judge said.
“The potential for both direct and indirect damage of what you said is simply incalculable,” he said.
Hamza “helped to create an atmosphere in which to kill has become regarded by some as not only a legitimate course but a moral and religious duty in pursuit of perceived justice”.
The judge said: “No one can now say what damage your words may have caused. No one can say whether your audience, present or wider, acted on your words.”
He added: “I am satisfied that you are and were a person whose views and the manner of expression of those views created a real danger to the lives of innocent people in different parts of the world.”