One issue in the Perfect 10 v. Google, Inc. case was whether Perfect 10, in seeking a preliminary injunction, bore the burden not only of establishing a likelihood of success on its prima facie case, but in also establishing it was likely to overcome any affirmative defenses Google asserted, in that case fair use. Judge Matz, following the district court decision in the Dr. Seuss case, held that Perfect 10 did bear that burden. The opinion, however, missed contrary authority, and perhaps most importantly, understandably did not discuss a Supreme Court opinion handed down the same day (February 21) that held to the contrary.
There is nothing special about fair use in this discussion: license, statute of limitations, or any other affirmative defense should be treated the same way. Indeed, there is nothing special about copyright: all civil cases, unless there is some statutory or precedential twist, should come out the same way. I encountered the issue for the first time in 1992, when the House Judiciary Committee was amending Section 107 to deal with fair use of unpublished works. At that time, a March 13, 1992 opinion from the Northern District of New York in College Entrance Examination Board v. Cuomo, 788 F. Supp. 134, 140 n. 7 (N.D.N.Y. 1992) had held, without citation to authority, that where the copyright owner seeks a preliminary injunction, the copyright owner bears the burden of disproving the defense. I thought that wrong, and in the House Judiciary Committee report, H.R. Rep. 102-836, 102d Cong., 2d Sess. 3 n. 3 (1992), I inserted the statement that it was erroneous, noting that even the College Entrance Examination Board court agreed when a plaintiff sought summary judgment, it did not bear the burden of disproving fair use. Subsequently, the New York judge, in College Entrance Examination Board v. Pataki, 889 F. Supp. 554, 564 (N.D.N.Y. 1995), noted the House report criticism and changed course.
Meanwhile, on the left coast, influenced by a comment in Judge William Schwarzer's work, California Practice Guide, Federal Civil Procedure Before Trial , volume 2, paragraph 13:47, courts followed the Cuomo approach. The argument was raised by Napster, and on appeal, the Ninth Circuit had this to say, 239 F.3d 1004, 1014 n.3 (9th Cir. 2001):
"FN3. Napster asserts that because plaintiffs seek injunctive relief, they have the burden of showing a likelihood that they would prevail against any affirmative defenses raised by Napster, including its fair use defense under 17 U.S.C. § 107. See Atari Games Corp. v. Nintendo, 975 F.2d 832, 837 (Fed.Cir.1992) (following Ninth Circuit law, and stating that plaintiff must show likelihood of success on prima facie copyright infringement case and likelihood that it would overcome copyright misuse defense); see also Dr. Seuss Enters. v. Penguin Books USA, 924 F.Supp. 1559, 1562 (S.D.Cal.1996) (“The plaintiff's burden of showing a likelihood of success on the merits includes the burden of showing a likelihood that it would prevail against any affirmative defenses raised by the defendant.”), aff'd,109 F.3d 1394 (9th Cir.1997); Religious Tech. Ctr. v. Netcom On-Line Communication Servs., 923 F.Supp. 1231, 1242 n. 12 (1995) (same); 2 William W. Schwarzer et al., California Practice Guide, Federal Civil Procedure Before Trial ¶ 13:47 (2000) (advising that when a preliminary injunction is sought “plaintiff must demonstrate a likelihood of prevailing on any affirmative defense as well as on plaintiff's case in chief”). But see Fair Use of Copyrighted Works,H.R. Rep. 102-836 n.3 (criticizing a Northern District of New York case in which “the district court erroneously held that where the copyright owner seeks a preliminary injunction, the copyright owner bears the burden of disproving the [fair use] defense”); see also 1 William F. Patry, Copyright Law & Practice, 725, 725 n.27 (1994) (citing cases placing burden on defendant at preliminary injunction stage).The district court stated that “defendant bears the burden of proving ··· affirmative defenses.” Napster, 114 F.Supp.2d at 912. Plaintiffs assert that the district court did not err in placing the burden on Napster. We conclude that even if plaintiffs bear the burden of establishing that they would likely prevail against Napster's affirmative defenses at the preliminary injunction stage, the record supports the district court's conclusion that Napster users do not engage in fair use of the copyrighted materials."
On February 21, 2006, however, a unanimous Supreme Court seems to have foreclosed the argument, in an opinion written by Chief Justice Roberts, Gonzales v. O Centro Espirita Beneficente Uniao de Vegetal. That case involved one of those wonderful religious groups that commune with God in part by taking hallucinogenic drugs, in this case, hoasca, whose effects are described in this link to a 1996 article in the Journal of Nervous and Mental Disorders (my grandfather was a psychiatrist, and the journal is a must bedtime reading for me). The sect and the drug is from the Amazon Rainforest (or what is left of it), but there is a small outpost in the U.S. that wished to import it for religious purposes. The feds classified the sacrament as a controlled substance and said no. The sect sued, seeking a PI as a violation of RFRA (42 U.S.C. 2000b et al). The feds did not contest taking the drug was part of a sincere exercise of religion.
For our purposes, the issue came down to this: plaintiff concededly made out its prima facie case of a violation of RFRA. The feds raised the affirmative defense (under the statute), that it has a compelling interest in banning the drug. It offered evidence of such an interest, which the plaintiff sought to rebut. The district judge (affirmed by the court of appeals), found the evidence on the affirmative defense to be in equipoise. The issue was then, whether it was appropriate to grant a PI in that posture: did the plaintiff have to introduce a scintilla of evidence beyond equipoise, show, in other words, a likelihood of succeeding on the merits of not only its prima facie case (which the feds conceded it had), but also in disproving the feds affirmative defense? The trial court, the court of appeals, and the Supreme Court unanimously held plaintiffs do not bear that burden.
Here is the relevant discussion:
"The Government argues that, although it would bear the burden of demonstrating a compelling interest as part of its affirmative defense at trial on the merits, the [plaintiff] bore the burden of disproving the asserted compelling interests at the hearing on the preliminary injunction. This argument is foreclosed by our recent decision in Ashcroft v. ACLU, 542 U.S. 656,  (2004). ... The point [is] that the burdens at the preliminary injunction stage track the burdens at trial."
I think that fairly settles the matter.