[Excerpt] This report describes the Keystone XL pipeline project, as proposed by TransCanada in its May 4, 2012, Presidential Permit application, and the process that the State Department is obligated to complete in processing that permit application. It also summarizes issues that arose during the 2008 permit application process, particularly those that may affect the current permit application. This report also summarizes key arguments that have been raised, both for and against the pipeline, by the pipeline’s developers, state and federal agencies, environmental groups, and other stakeholders. Finally, the report reviews the constitutional basis for the State Department’s authority to issue a Presidential Permit, and opponents’ possible challenges to this authority.