All but lost in the hubbub over the failure of health care reform was news that the federal government on Friday formally greenlighted the Keystone XL Pipeline, issuing a long-sought permit that will allow the project to move forward.

Great news for TransCanada Corp., but perhaps bittersweet for its lawyers at Sidley Austin. A stellar team of litigators was poised to break new legal ground with two novel challenges—one on constitutional grounds, the other seeking $15 billion in redress under the North American Free Trade Agreement.