Ahmed Ressam was arrested in December 1999 in Port Angeles, Wash., after he drove off a ferry from British Columbia with a trunk full of explosives.
U.S. District Judge John C. Coughenour had twice ordered him to serve 22-year terms, but both times the sentences were reversed on appeal.
Ressam's lawyers had conceded that he should face at least three decades to satisfy the appeals courts.
The Justice Department had sought life in prison because of the mass murder he intended to inflict and because he recanted his co-operation with federal investigators.
Coughenour said Wednesday that "this case provokes our greatest fears."
Ressam arrived in Canada in February 1994 and sought refugee status shortly after landing at Mirabel Airport near Montreal. He failed to show up for an immigration hearing in April 1995, and his claim was rejected. He appealed in Federal Court but that too was turned down.
Ressam was ordered deported at the end of July 1995, but was later released under condition that he check in with Immigration office once a month.
In March 1997, a moratorium was issued on deporting Algerians, under the reasoning that people should not be forced back to a country in the midst of civil war, so Ressam remained in Montreal until 1999 when he was arrested.
A customs official noticed that Ressam appeared suspicious when he drove off the ferry from Victoria on Dec. 14, and signalled him to stop for further inspection. His arrest, after a brief foot chase, prompted fears of a terrorist attack and the cancellation of Seattle's New Year's Eve fireworks.
Ressam started co-operating after he was convicted and was interviewed more than 70 times by terror investigators from the U.S., Canada, Great Britain, Spain, Italy, Germany and France.
Information he provided helped to convict several terror suspects; prompt a famous August 2001 FBI memo titled "Bin Laden determined to strike in U.S.;" and contribute to the arrest of suspected Osama bin Laden lieutenant Abu Zubaydah, who remains in custody without charges at Guantanamo Bay, Cuba.
Ressam subsequently recanted all of his co-operation when it became clear that the prosecutors weren't going to recommend that he serve less than 27 years in prison.
The recanting forced the Department of Justice to drop charges against two suspected co-conspirators, Samir Ait Mohamed and Abu Doha.
_ With files from The Canadian Press.