The Keystone XL pipeline to bring Canadian crude to the U.S. has hit another barrier. This project has been on the drawing board for a full decade now, and the latest issue is the Trump administration’s paperwork. Just after taking office, the administration decided the project could move forward. But late yesterday a U.S. court blocked a Trump administration permit for construction of the pipeline .Why? On grounds that the U.S. government had not fully done its homework. The court sent the assignment back to Washington for more review of the environmental and business risks.