If he really wants to, Trudeau can invoke section 92 (10)(c), of the Constitution, which gives him the legal jurisdiction to by - pass the province and, for the «general advantage of Canada,» build the pipeline. (macleans.ca)
Bill S - 245, An Act to declare the Trans Mountain Pipeline Project and related works to be for the general advantage of Canada (sencanada.ca)
Hon. Douglas Black moved second reading of Bill S - 245, An Act to declare the Trans Mountain Pipeline Project and related works to be for the general advantage of Canada. (dougblack.ca)