United States Senate, Committee on the Judiciary, Copyright Law Revision (Senate Report No… (1975)
“ On the other hand, endowing a copyright claimant who has obtained a certificate with a rebuttable presumption of the validity of his copyright does not deprive the defendant in an infringement suit of any rights; it merely orders the burdens of proof. The plaintiff should not ordinarily be forced in the first instance to prove all of the multitude of facts that underlie the validity of his copyright unless the defendant, by effectively challenging them, shifts the burden to him to do so. ”
