What do Pretty Woman, National Lampoon's Animal House, and The Godfather have in common? Sure, they're all great movies. But each also contained music in the public domain.

What is the Public Domain?

It's any creative work without copyright protection. You can use public domain material any way you want, and you don't have to get anyone's permission to do so. And best of all, everything in the public domain can be used for free. Most public domain works had copyrights that expired. In addition, all publications created by the U.S. government such as the latest version of the CIA World Factbook are automatically in the public domain.

How can you tell if a Certain Work is in the Public Domain?

First, find out the author and publication date of the work in question. Next, use the following as a guide.

• Works created after January 1, 1978

You'll have to wait awhile for these to enter the public domain. Their copyright term is the lifetime of the author plus another 70 years.

• Works created before January 1, 1978 but not published

If the work was still unpublished by 12/31/2002, it has a copyright term of the author's lifetime plus 70 years. If the work is published or registered by 12/31/2002, it received automatic protection until 2047, in addition to a copyright term of the author's lifetime plus 70 years.

• Works Published from 1964 - 1977

These have an original copyright of 28 years. But instead of falling into the public domain, they automatically received 67 more years of protection.

• Works Published from 1923 - 1963

These also had 28 years of original copyright protection. But they only received another 67 years if the author decided to renew the copyright.

• Works Published before 1923

These works are most likely in the public domain and can be used free of charge. But a little caveat: some foreign works were pulled out of the public domain by a series of recent trade agreements. Therefore, make sure you investigate the availability of such a work before using it.

Other Ways to Find Out if a Work is in the Public Domain

Still not sure if a particular work is in the public domain?  You may be able to do some research at your local library, or online using a special automated catalog system. In case you still come up empty, you can always search the archives of the U.S. Copyright Office. Of course, you'll have to travel to Washington D.C. first. And if you manage to make the trip, be prepared to go through several catalogs, records, and documents. Also, bring some extra cash: certain records can only be viewed by the public for a fee.

And if you don’t mind paying (yes, another fee) for some top-notch service, have the experts at the Copyright Office do your research. They know where to look and what to look for. And afterwards, you'll receive a complete search report.

Using Public Domain Material

You should keep in mind that a particular adaptation or translation of a public domain work may be protected by copyright. For example, you're free to use the original Herman Melville's 19th century classic, Moby Dick, because it's clearly in the public domain. But you couldn't use rewritten text from a 2004 children's edition of Mr. Melville's masterpiece unless you first receive permission from the new author.

Avoid potential legal problems by using the author's original work, or a version that's also in the public domain. Using public domain works can save you time and money. But make sure a work is actually in the public domain before you use it. And if you're in doubt, a search may have to be done, by either you or the Copyright Office. But it's usually worth the effort to avoid possible litigation.