"The Plan explicitly does not aim at complying with the Kyoto Protocol, and therefore does not conform to the requirements of the Act," lawyers Chris Paliare and Andrew Lokan wrote in the application, filed on behalf of Ecojustice Canada and Friends of the Earth Canada.

"On its terms, the Plan provides that emissions of greenhouse gases will far exceed the levels required by the Kyoto Protocol," they said.

A Federal Court judge could theoretically respond to the application by ordering the government to file a new plan that is in keeping with the Kyoto Protocol.

"In this particular case, even though the Act is highly complicated, there are key aspects of the fudged implementation plan that does indicate a 'thumbing of the nose' against the law," University of Ottawa law professor Errol Mendes said in an interview. "If the Ecojustice lawyers can keep it simple, there is a sound basis for seeking a declaration that the government is not complying with its own Act," Prof. Mendes said.

He said the case is particularly interesting because the country may be on the verge of a succession of minority governments. "If we have legislation on more than one area passed by the combined numbers of the opposition, can the minority government just ignore the law passed by Parliament or fudge any mandate to implement it by regulation?" Prof. Mendes said.

Several legal precedents exist in which courts forced provinces or the federal government to respect its own environmental legislation, according to Albert Koehl, a lawyer for Ecojustice.

"The court is not going to be stepping into the shoes of the Minister of the Environment or the Prime Minister," Mr. Koehl said in an interview. "It would simply look at whether the plan complies with the Act."

Mr. Paliare said the case boils down to whether a government can blithely ignore its own legislation: "This case is about being accountable to the will of Parliament," he said.

Garry Keller, director of communications for federal Environment Minister John Baird, said in a statement the department would have no comment on cases before the courts.

The Conservatives have consistently maintained that years of inaction on the part of their Liberal predecessors makes it impossible to meet the targets without serious consequences for the economy.