Recently Amazon sold copies of George Orwell's Animal Farm and Ninteen Eighty-Four to customers. When it discovered that the supplier it had bought the books from didn't have a license for U.S. distribution of these works (where they are still under copyright), Amazon deleted the two e-books from customers' accounts. When the customers re-synced their kindles, Amazon's software re-configured the Kindles to agree with the content of the accounts on Amazon's computers--which meant that the two ebooks were deleted from those customers' Kindles.
Much is being written about the incident. The point I want to stress is this: If Nineteen Eighty-Four was first published in the U.S. in 1949 (the year of its publication in the U.K.,) and if the term of U.S. copyright had stayed at 56 years as it was in 1949, then Nineteen Eighty-Four would have been promoted to the public domain on January 1st, 2006, and the unlicensed copies Amazon had acquired would have been legal for distribution in the U.S. Likewise Animal Farm, if the year of its U.S. publication was 1945, would have entered the U.S. public domain on January 1st, 2002. It too would then have needed no special license for U.S. distribution.