Alberta wants to have its say when British Columbia goes to the Supreme Court for a ruling on who is in charge of interprovincial projects like pipelines.
The Alberta government says it has filed a notice of intervention in B.C.'s appeal to the top court.
Alberta Premier Jason Kenney says the B.C. Court of Appeal made it clear in its May ruling that the federal government, not the provinces, has sole authority over projects that cross provincial boundaries.
Kenney says the B.C. court action is a bid to limit Alberta's oil resources from getting to the coast and, from there, fetching a better price overseas.
Alberta and B.C. have been battling for years over energy issues, particularly the Trans Mountain pipeline expansion.
Alberta has already passed a law allowing it to cut existing oil shipments to B.C. in retaliation if it so chooses, which British Columbia is also challenging in court.