That review is currently underway, but under new rules the board has opted against allowing interveners to directly question the company, and all comment must be submitted in writing.
ForestEthics says in its motion to the Federal Court of Appeal that the new process unfairly restricts public participation, rejects participants' applications, and refuses to hear concerns related to climate change and oilsands development.
ForestEthics says it is also asking the court to impose an interim injunction on the pipeline-review process until its legal challenge is resolved.
The group says its application to the Federal Court of Appeal follows an unsuccessful constitutional challenge that was filed to the board.
The proposed expansion would almost triple the pipeline's capacity, bringing about 900,000 barrels a day from Alberta's oilsands to a tanker terminal in Metro Vancouver.