You must register your copyright with the U.S. Copyright Office before you are legally permitted to bring a lawsuit to enforce it.

You can register a copyright at any time, but registering it promptly may pay off in the long run. "Timely registration" -- that is, registration within three months of the work's publication date or before any copyright infringement actually begins -- makes it much easier to sue and recover money from an infringer. Specifically, timely registration creates a legal presumption that your copyright is valid, and allows you to recover up to $150,000 (and possibly lawyer fees) without having to prove any actual monetary harm.

You can register your copyright by filing a simple form and depositing one or two samples of the work (depending on what it is) with the U.S. Copyright Office. There are different forms for different types of works -- for example, form TX is for literary works while form VA is for a visual art work. Forms and instructions may be obtained from the U.S. Copyright Office by telephone, 202-707-9100, or online at www.copyright.gov.

Registration currently costs $45 per work. If you're registering several works that are part of one series, you may be able to save money by registering the works together (called "group registration").

For detailed information on the registration process, see The Copyright Handbook, by Stephen Fishman (Nolo).

Until 1989, a published work had to contain a valid copyright notice to receive protection under the copyright laws. But this requirement is no longer in force -- works first published after March 1, 1989 need not include a copyright notice to gain protection under the law.

But even though a copyright notice is not required, it's still important to include one. When a work contains a valid notice, an infringer cannot claim in court that he or she didn't know it was copyrighted. This makes it much easier to win a copyright infringement case and perhaps collect enough damages to make the cost of the case worthwhile. And the very existence of a notice might discourage infringement.

Finally, including a copyright notice may make it easier for a potential infringer to track down a copyright owner and legitimately obtain permission to use the work.

A copyright notice should contain:

• the word "copyright"
• a "c" in a circle (©)
• the date of publication, and
• the name of either the author or the owner of all the copyright rights in the published work.

For example, the correct copyright for the fourth edition of The Copyright Handbook, by Stephen Fishman (Nolo), is Copyright © 1998 by Stephen Fishman.

If someone violates the rights of a copyright owner, the owner is entitled to file a lawsuit in federal court asking the court to:

• issue orders to prevent further violations (restraining orders and injunctions)
• award money damages if appropriate, and
• in some circumstances, award attorney fees.

Whether the lawsuit will be effective and whether damages will be awarded depends on whether the alleged infringer can raise one or more legal defenses to the charge.

Common legal defenses to copyright infringement include:

• Too much time has elapsed between the infringing act and the lawsuit (the statute of limitations defense).
• The infringement is allowed under the fair use doctrine. (For more information, see Nolo's article The 'Fair Use' Law: When Use of Copywrited Material is Acceptable.)
• The infringement was innocent (the infringer had no reason to know the work was protected by copyright).
• The infringing work was independently created (that is, it wasn't copied from the original).
• The copyright owner authorized the use in a license.

If someone has good reason to believe that a use is fair -- but later finds herself on the wrong end of a court order -- she is likely to be considered an innocent infringer at worst. Innocent infringers usually don't have to pay any damages to the copyright owner, but do have to cease the infringing activity or pay the owner for the reasonable commercial value of that use.