OTTAWA -- The federal government will intervene in British Columbia's reference case over the $7.4-billion Trans Mountain pipeline expansion, Justice Minister Jody Wilson-Raybould said Thursday.

The case filed in the B.C. Court of Appeal asks if the province has jurisdiction to regulate the transport of oil through its territory, a key question in the political battle over the project.

Wilson-Raybould said Ottawa's view will prevail.

"We are confident in Parliament's jurisdiction and will intervene on the question in order to defend our clear jurisdiction over interprovincial pipelines," she said in a statement.

While project architect Kinder Morgan has halted investment in the expansion unless and until the clouds of uncertainty looming over it can be cleared, giving the government a May 31 deadline, the federal government remains a strong -- and increasingly adamant -- backer.

Prime Minister Justin Trudeau has vowed the pipeline will be built, and has instructed Finance Minister Bill Morneau to sit down with Kinder Morgan to find a financial solution that will soothe their investors.

He also promised legislation that would reaffirm Ottawa's authority to press ahead with a development deemed to be in Canada's national interest.

B.C. Premier John Horgan, meanwhile, has said he will use every tool available to stop the pipeline, arguing that his province has every right to protect its residents, economy and environment from the threat of an oil spill.

Trudeau has made the pipeline a central component of a vision that couples economic expansion with environmental stewardship.

Trudeau said the pipeline was approved by his government in 2016 after a rejigged environmental assessment and Indigenous consultation process, and only in concert with the Liberal climate change and oceans protection plan.

Approval came in consultation with the previous B.C. Liberal government, which gave its consent to the project after its own conditions were met.

Horgan's election last year changed everything. His minority government exists at the pleasure of the Green party, and on condition of his continued opposition to the project.