 To avoid individual states' attempts at creating their own copyright systems, Congress passed the Copyright Act of 1790, based on Great Britain's Statute of Anne.Over the decades since, copyright in the United States has become a more complicated system with longer terms and more tests, and has been the subject of many decisions by the Court.The Supreme Court was the source of a number of concepts in the field, including fair use, the idea-expression divide, the useful articles or separability doctrine, and the uncopyrightability of federal documents.