Here is another article that describes the two lawsuits that TransCanada is pursuing.
I don't think the second case will prevail.After taking a blow by the Obama administration, TransCanada Corp. is launching a two-pronged legal attack on the president's rejection of the Keystone XL pipeline that some attorneys say may pay off.
The Canadian energy company yesterday announced plans to challenge the administration on two fronts. TransCanada said it's seeking $15 billion in damages from the U.S. government under the North American Free Trade Agreement, claiming that the rejection of the proposed pipeline was political and deprived investors of billions of dollars sunk into the project.
The company is also suing the administration in a federal district court in Texas, alleging the president surpassed his constitutional authority by vetoing the pipeline.