For almost three years Dutch authorities have struggled without success to punish Samir Azzous, 19,for what they see as plotting terrorism.



Police records show that he was first placed under surveillance in early 2003, when he was in high school, after he was stopped at the Ukrainian border while trying to join Islamic militants in Chechnya.He was arrested months later in Amsterdam but released in days for lack of evidence. Arrested again in June 2004 on terrorist-related charges, he was convicted only of weapons possession. The police had found an array of materials that could be used to make bombs at his home in Amsterdam, including detonators and a yellow plastic lemon juice bottle, with bits of fertilizer inside, attached to a Christmas tree bulb.



They had also discovered crude hand-drawn sketches of some of the Netherlands’ most important symbols of power, including the Parliament, the Amsterdam airport, the Ministry of Defense and the Dutch nuclear reactor, as well as CD’s, videos and Internet sites showing how to make explosive devices.



In October, prosecutors arrested him for a third time, with new evidence, and will put him and six others on trial. The prosecution says it is confident that its case is strong this time. But since no terrorist act was committed, it faces a tough challenge: proving that Mr. Azzouz’s seeming intentions constituted crimes.



The problem resonates throughout Europe, as investigators and prosecutors grapple with how to stop what appear to be terrorist plots that are still being planned. Preventive detention in the face of a perceived threat is a useful but limited tool.The difficulty also has echoes in civil liberties disputes roiling the United States, but it is particularly acute in the Netherlands, with its tradition, extending for decades, of protecting the rights of the individual against the intrusion of the state.



“People with intentions cannot be convicted if there is no link with transforming their intentions into action,” the Dutch justice minister, Jan Piet Hein Donner, said in an interview. “Otherwise, I’d be convicting people for their ideas.”



Dutch authorities say the learning curve has been steep in their prosecution of terrorist cases since the daylight murder of the filmmaker Theo van Gogh last year, for which Muhammad Bouyeri, a Dutch-born 27-year-old of Moroccan descent, was convicted.The murder shattered the image of the Netherlands as a tolerant haven immune to terrorism by Islamic radicals and prompted the passage of a law that makes it a crime to be a member of a “terrorist” organization.



Victor Koppe, his lawyer, said he planned to challenge the use of intelligence reports in court. He will also argue that while Mr. Azzouz’s views may be extreme, they are not criminal. “Intentions,” he said, “are not crimes.”



Mr. Azzouz testified on Dec. 21 telling the judges: “We reject you. We reject your system. We hate you. I guess that about sums it up.”



Civil liberties can still trump security in the Netherlands. Early in December, a young Muslim mother of three from Amsterdam identified only as Jolanda W. won a ruling against police officers she had accused of stalking her.”One cannot rule out that these measures put important psychological pressure upon the person harassed,” Judge A. J. Beukenhorst said in his ruling. “Islamic belief,” he added, “cannot by itself be the reason for harassment.”



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