A Canadian court blocked a major oil pipeline project, ruling that the country’s federal government didn’t properly consider the impacts of the controversial C$7.4-billion, 715-mile pipeline.

In a major blow for Prime Minister Justin Trudeau and his Liberal Party government, the Federal Court of Appeal overturned the federal approval of the Kinder Morgan Inc.’s Trans Mountain Pipeline expansion project Thursday, effectively blocking it for the time being. The decision comes months after Trudeau agreed to buy the Trans Mountain expansion project in order to sell it to a new owner and rescue the project from its financial difficulties.

The development is yet another result of a years-long effort across the United States and Canada by environmentalists and indigenous groups to block major oil and natural gas pipeline projects.

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Similarly to the proposed Keystone XL pipeline project, Trans Mountain brings oil from the booming oil sands of Alberta, Canada, to a market for sale or refining. The expansion project is meant to bring a new, parallel pipe to the existing one.

Specifically, Justice Eleanor Dawson wrote in the court’s Thursday decision that the National Energy Board, which was responsible for reviewing the project prior to government approval, didn’t properly account for oil tankers that would be brought to the Pacific coast of British Columbia to take the oil from the pipeline.

“The unjustified exclusion of marine shipping from the scope of the project led to successive, unacceptable deficiencies in the board’s report and recommendations,” Dawson wrote, noting that the Governor in Council “could not rely on the board’s report and recommendations when assessing the project’s environmental effects and the overall public interest.”

The board’s review concluded that the project wouldn’t have significant environmental consequences.

Bill Morneau, Trudea’s finance minister, tweeted Thursday that the government was reviewing the decision and he would speak more thoroughly about it later in the day.