The U.S. Supreme Court in Fourth Estate Pub. Benefit Corp. v. Wall-Street.com, LLC clarified that copyright registration occurs, and a claimant may commence a copyright infringement suit, once the U.S. Copyright Office registers a copyright. The Court, in an opinion issued on March 4, 2019, found that this was the only satisfactory reading of Title 17 U.S.C. Section 411(a)'s text.
This decision resolves a division among the U.S. Court of Appeals. For instance, the Ninth Circuit had held that registration has been made and an infringement suit could commence when the copyright claimant's complete application is received by the Copyright Office. This is no longer valid.
The Supreme Court acknowledged that there are limited exceptions to the registration rule. Preregistration allows an author of a work that is vulnerable to predistribution infringement to enforce the author's rights before obtaining a registration. The Supreme Court used this exception to guide its reading of the application vs. registration question: "A copyright owner who fears prepublication infringement would have no reason to apply for preregistration, however, if she could instead simply complete an application for registration and immediately commence an infringement suit."
While the claimant may not commence a suit until registration, the owner may eventually recover damages for the past, preregistration infringement. The owner may also seek an injunction barring the infringer from continuing violation of her rights once the Register grants or refuses the registration.