The Trans Mountain pipeline expansion that the Trudeau government purchased for $4.5 billion got a boost today in British Columbia’s court of appeal, which ruled that federal regulatory authority is supreme for transboundary energy projects.

In March, the court began hearing intervenors in New Democrat Premier John Horgan’s challenge that the province could effectively control transit access through amending B.C.’s own environmental legislation.

In its ruling, the appeal court indicated that the National Energy Board’s regulatory purview trumps the provinces’ attempt exact additional directives.

“This alone threatens to usurp the role of the (National Energy Board), which has made many rulings and imposed many conditions to be complied with by Trans Mountain for the protection of the environment,” writes Justice Mary Newbury on behalf of the appeal court’s panel.

Following a First Nations challenge of the original NEB decision to twin existing pipeline infrastructure in the Federal Court of Appeal last year, the Liberal government announced its intentions to buy the entire stake from Kinder Morgan.

On August 30, 2018, the federal court delivered its decision quashing NEB’s approval, the same day 99 percent of the Houston Texas firm’s shareholders voted to sell its Trans Mountain interests to Canada.

British Columbia’s case is expected to be appealed to the Supreme Court of Canada, while the Trudeau government has extended its own deadline on whether to proceed with twinning the nationalized pipeline to June 18.