The Alberta Utilities Commission approved AltaLink's $1.5-billion Western Alberta Transmission Line last month.
Landowners who live along the line's route between Edmonton and Calgary are seeking leave to challenge the decision March 28 in the Alberta Court of Appeal.
In their application, they suggest the main purpose of the line is to export power from the province.
Joe Anglin of the Opposition Wildrose says his party supports the court challenge, because the line would mean higher electricity bills for consumers.
AltaLink, a subsidiary of SNC-Lavalin (TSX:SNC), has said it hopes to start building the line this year and finish by 2015.