Reuters: A coalition of environmental groups on Friday launched a legal challenge to the preliminary approval last month for Enbridge Inc's C$7.9 billion ($7.21 billion) Northern Gateway pipeline project, filing suit to prevent Canada's government from using the approval in its final decision on the line. The groups are objecting to the approval granted Northern Gateway last month by the Joint Review Panel. The panel, which held 18 months of hearings into Northern Gateway, concluded the project posed little...