If a creator uses works in the public domain (e.g. Shakespeare play, the Bill of Rights, etc.), how does this affect the copyright registration application process?
If a creator uses an appreciable amount of preexisting material, such as public domain material, material owned by third parties, or previously published material, the creator must exclude that material in the application for registration. The claim will extend only to the new material contributed by the derivative, compilation, or collective work author.
If the work contains a sufficient amount of new authorship, if the preexisting public domain material is adequately excluded in the application for registration, and if the remainder of the application is in proper form, the registration process is relatively straightforward. However, where preexisting works are not excluded properly, it is likely that the Office will correspond with the applicant, which will delay the registration process.
Rob Kasunic, Director of Registration Policy and Practices at the U.S. Copyright Office