Nor can we endorse the defendant's claim that its good-faith belief that incorporation of elements from “Atomic Dog” was fair use negates willfulness. True, we held in Princeton University Press that “one who has been notified that his conduct constitutes copyright infringement but who reasonably and in good faith believes the contrary is not ‘willful’ for these purposes.” But, in this case the defendant did not present any evidence to establish a basis for their claim of good faith, which is a defense to willfulness only if it is formed prior to the infringing acts. , we have allowed a good-faith belief in fair use to negate willfulness only if a defendant has taken reasonable steps to assure fair use before infringement, not as a “post-hoc rationalization concocted to skirt liability.” (claim of good faith unavailing where creator of infringing karaoke CDs continued to distribute them after receiving notice of infringement and made no legal inquiries about fair use).