There have been many changes to the U.S. copyright law since 1790, when Congress first enacted the United States copyright law. The law gave writers exclusive rights to publish and sell maps, charts and books for a period of fourteen years.

They could renew the copyright for another fourteen years. In the 19th century, copyrights became available for pictures, photographs, paintings, and drawings. In 1909, the copyright law covered rolls for player pianos. Since 1976, copyright law has expanded to include cable, digital photography, TV, computer software, tapes, CDs, DVDs, and, most recently, MP3s.

The length of copyright terms has also gradually increased. Up until 1998, copyrights lasted for the life of the author plus an additional fifty years, before they reverted to public domain (anyone could then use the item without charge). But in 1998, the Sonny Bono Copyright Term Extension Act extended the duration of copyrights by twenty years. The act was supported by a group of large corporations, led by Disney. Most of Disney's famous characters, Mickey Mouse, Donald Duck, Goofy and all the rest, were scheduled to enter the public domain between 2000 and 2004. But now other artists and companies won't be able to use them in their books and movies and songs until at least 2019, which means that Disney has another thirteen years of making money off Disney's creations.

Whether the Copyright Law is in your favor depends on which side of the copyright table you're sitting at (publisher or supplier). Hint: Lately, the copyright pendulum has been swinging to the publishers. The most recent issue to cause questions has been "copyright orphans." These are works to which publishers cannot find the author, to be able to either get permission to use the work, or determine it can be considered "fair-use," and used without permission or payment.