OTTAWA — An Ontario court ruling has revived debate over the definition of terrorism under Canadian law, raising questions that could have repercussions in two key cases.

The judgment, delivered by Justice Laurence Pattillo of Ontario Superior Court two weeks ago, upheld a contentious section of the federal Anti-Terrorism Act that defines terrorism as a crime motivated by ideological, political or religious considerations.

The immediate effect of the little-publicized decision was to clear the way for extradition of Piratheepan Nadarajah and Suresh Sriskandarajah, two men with alleged ties to the Tamil Tigers, to face terrorism financing and procurement charges in New York.

The longer-term significance was that Pattillo flatly contradicted an earlier decision by Justice Douglas Rutherford, who ruled in 2006 that the definition violated the constitutional guarantees of freedom of thought, expression, belief and association enshrined in the Charter of Rights.

That ruling came in the case of Momin Khawaja, the first person charged under the 2001 anti-terror law that was pushed through Parliament following the 9-11 attacks south of the border.

Rutherford severed the offending portions from the rest of the law and let the trial proceed — resulting in a conviction of Khawaja and a sentence last week to 10 1/2 years in prison for his role in a British-based conspiracy to wage jihad against western interests.

The latest developments seem certain to spark a new round of court hearings — and force the Conservative government to decide whether it will continue defending the terrorism definition adopted under the former Liberal rule of Jean Chretien.

John Norris, the Toronto-based lawyer for one of the accused Tamils, has already filed papers to take the extradition case to the Ontario Court of Appeal.

His argument is that the so-called motive clause in the law should be thrown out, effectively quashing the extradition effort and sending federal lawmakers back to the drawing board.

"If you find a serious constitutional flaw in the very definition of the offence, the only appropriate remedy is to strike the whole thing down and let Parliament go back and reconsider," said Norris.

Lawrence Greenspon, the lawyer for Khawaja, hasn’t formally decided yet whether to launch an appeal of his client’s conviction and sentencing.

But he acknowledged in an interview that his opinion of the motive clause hasn’t changed since he first raised it three years ago.

"You don’t single out an individual because of their political, religious or ideological beliefs," said Greenspon. "To do so violates fundamental freedoms."