The verdict? B.C's top court said proposed legislation to limit the flow of increased amounts of "heavy oil" into B.C. would be in direct conflict with federal jurisdiction over interprovincial pipelines.

Their decision was unanimous.

Written by Justice Mary Newbury, the66-page ruling states that "Even if it were not intended to 'single out' the TMX pipeline, it has the potential to affect (and indeed 'stop in its tracks') the entire operation of Trans Mountain as an interprovincial carrier and exporter of oil"

"At the end of the day, the NEB is the body entrusted with regulating the flow of energy resources across Canada to export markets … The project affects the country as a whole, and falls to be regulated taking into account the interests of the country as a whole."

The decision is clearly a significant blow to B.C.'s NDP government who will no doubt appeal the decision to the Supreme Court of Canada.

"From this proposition, it is a short step to Canada's argument that the immediate purpose and undeniable effect ... is to provide a means by which the province may impede additional heavy oil originating in Alberta from being transported through British Columbia generally, and thus 'frustrate' the project in particular," the ruling says.

While the decision does indeed note that both levels of government have jurisdiction over aspects of the environment and have the right to introduce legislation to mitigate environmental harm, the judges found that jurisdiction over interprovincial pipelines was given to Ottawa through the Constitution Act to "deal with just this type of situation, allowing a single regulator to consider interests and concerns beyond those of the individual province(s)."

Newbury wrote the provinces and Ottawa should play important roles in the management of the environment, but said B.C.'s proposed regulation was not "legislation of general application, but is targeted at one substance in one (interprovincial) pipeline."