Action on unregistered Copyright Infringement.  An interesting article from  Adam

source: http://www.legalmatch.com/law-library/article/unregistered-copyrights.html
Once a work is “fixed” in a “tangible medium of expression,” it is automatically protected by copyright. Registration is not necessary to receive copyright protection. An unregistered copyright entitles you to reproduce, sell, and perform the copyrighted work. Beyond this, your rights are limited if your copyright is not registered, especially if you have distributed your work through a copyleft agreement.

Bringing Suit for Unregistered Copyrights
You cannot bring a suit for copyright infringement without first registering your copyright. It is possible to sue for an injunction, which …