Understanding Copyright Law
Any original, creative item fixed in tangible form is eligible for copyright protection. Items do not need to be registered or display a copyright notice.The burden for enforcing copyright generally falls to the person who owns the rights to the item -- most often the item's creator. This means that if someone has created something that they do not wish to copyright, you may not be sued if you copy it. However, because there's no way to know for certain if an item is copyrighted or if its owner will enforce her rights, you should contact the owner of the item before using it. Copyright owners can send you a removal notice or request that your ISP remove the item if it is posted on the Internet.
Copyright owners used to be able to sue for copyright violations in state courts, but copyrights are now enforced through the federal court system. A copyright owner may send a take-down notice to someone who uses a copyrighted item without permission. Although registration is not always required in order to bring an infringement lawsuit, registering a copyright affords the owner many more remedies. Copyrights can be registered after a violation occurs, which means that an item's lack of registration does not necessarily protect violators from lawsuits.
Copyrights expire after a set term, so some previously copyrighted items may no longer be protected. Items copyrighted prior to 1923 are now in the public domain. Items published after 1923 but before 1963 are copyrighted for 28 years, and the rights owner can renew the copyrights for an additional 67 years. Items published after 1963 and before 1977 automatically receive protection for a total of 95 years. Items published after 1978 are eligible for copyright protection for the life of the author plus 70 years. Thus, most recently created or recently published items are very likely covered under U.S. copyright law.
Not all uses of copyrighted items are violations of copyright law. The Fair Use Doctrine allows limited-purpose use for educational, scholarly and some other purposes. You may quote a few lines in a paper, distribute handouts to students and engage in other uses that are not designed to make a profit. However, U.S. law provides no firm standards on what constitutes fair use. Quoting a few lines might, for example, be allowed, but quoting a full page might not. If you plan to use a work extensively for any purpose, you should seek permission beforehand.