Opinion of STEVENS, J. and their particular dispute, in which prejudgment interest would begin to accrue in 1985. See Kansas III, supra, at 14-16. Its compromise left open the door to the present litigation, for saying when prejudgment interest began to accrue did not answer on what the interest was accruing. The Court therefore must again decide what is too little or too much compensation for Colorado's depletion of the Arkansas. That weighing is as unnecessary now as it was before. Kansas is not entitled to prejudgment interest, and its exception seeks only to compound the windfall it received in Kansas III. I therefore agree with the Court that Kansas' second exception to the Special Master's Report should be overruled. JUSTICE STEVENS, concurring in part and dissenting in part. 1 With the exception of Part II, I join the Court's opinion. In dissenting from Part II, I adhere to the views that we expressed in Kansas v. Colorado, 533 U. S. 1, 13–16 (2001) (Kansas III).1 In Kansas III, in a compromise that was required in order to issue a judgment of the Court, we accepted the views of THE CHIEF JUSTICE and JUSTICE KENNEDY that prejudgment interest should run from 1985, the date the complaint was filed. Ibid. Like today's majority, I adhere to the judgment reflecting that compromise. Unlike the majority, however, I believe that prejudgment interest should run, starting in 1985, on all damages that accrued after Colorado "knew or should have known that it was violating" its compact with Kansas-i. e., from 1969. Id., at 15, n. 5. Such a result best respects the reasoning behind our conclusion in Kansas III that prejudgment interest is an appropriate component of the award of damages. In Kansas III, recognizing that a monetary award does not fully compensate for an injury unless it includes an inter 1 Kansas III was predated by Kansas v. Colorado, 514 U. S. 673 (1995), and Kansas v. Colorado, 522 U. S. 1073 (1998). Opinion of STEVENS, J. est component, we affirmed the Special Master's determination that the unliquidated nature of Kansas' claim did not by itself bar an award of prejudgment interest. Id., at 14. Nevertheless, equitable concerns persuaded a majority of the Court to overrule the Special Master's determination that prejudgment interest should begin to run in 1969, the date on which Colorado first knew, or should have known, that it was violating the Arkansas River Compact. Although we did not explicitly discuss the point in our opinion, we also agreed with the Special Master's decision to exclude from the principal amount on which interest would run any damages that had accrued prior to 1969.2 The methodology that led to that conclusion was the Master's appraisal of the equities-in his judgment, interest should not be imposed on the portion of the damages award that was attributable to relatively innocent conduct that occurred before 1969. See Report 106-107 ("The general lack of knowledge in the early years about pumping in Colorado and its impacts along the Arkansas River served to protect Kansas during the liability phase of the case against a claim of laches. The same degree of fairness, I believe, should now relieve Colorado of the obligation to pay full interest rates on damages from depletions during 1950-68 2 Kansas had objected to the Master's refusal to award interest on all damages accruing after 1950. See Brief for Plaintiff in Kansas III, O. T. 2000, No. 105, Orig., p. 25, n. 8. Although we did not discuss Kansas' exception to the Special Master's determination regarding the total amount of damages on which interest would run, we overruled the objection and thereby approved the Master's selection of the period after 1968 as the appropriate measure of damages on which interest should be paid. See Kansas III, 533 U. S. 1, 14 (2001); see also Third Report of Special Master 106-107 (hereinafter Report) (explaining that Colorado's awareness of its breach was central to the determination that interest should run on post-1968 damages). Today, the Court explains why it would be inequitable to give Kansas the relief that would be the equivalent of sustaining an objection that we overruled three years ago, but does not explain why we should not accept the Special Master's original determination that all post-1968 damages should bear interest. Opinion of STEVENS, J. period. . ."). But the Master did find that Colorado was required to pay interest on damages that occurred between 1969 and 1985. See ibid.; see also Brief for United States in Opposition to the Exceptions of Kansas and Colorado in Kansas III, O. T. 2000, No. 105, Orig., p. 27 ("For the period from 1969 to the date of judgment, the Master recommended that Kansas be awarded prejudgment interest"). Our opinion did not reject that portion of his judgment, and did not contain any suggestion that he had erred in that respect. See 533 U. S., at 12, 14. The happenstance that we selected, as a compromise, the date the complaint was filed as the date on which interest should begin to accrue should have no bearing on the principal amount of damages that gave rise to the interest obligation. Thus, I believe that the Special Master's Fourth Report erred in its conclusion that we meant to limit the principal amount of damages to those that occurred after 1985. Surely if this were an ordinary tort case involving a single harm-causing event, an award of prejudgment interest would apply to the entire damages recovery, not just to the portion that resulted from events occurring after interest began to accrue. See Funkhouser v. J. B. Preston Co., 290 U. S. 163, 168 (1933). Indeed, were this an ordinary case, we would no doubt have awarded prejudgment interest in the entire amount that Kansas requested in Kansas III. This, however, is a unique case in which unusual equities necessitated a compromise designed to resolve a dispute between two States. Thus, I agree with the majority that the Special Master was correct in rejecting Kansas' argument that the principal on which interest should run should be “the nominal damages occurring from 1950 through 1984.” App. to Fourth Report 15. However, the fact that Kansas' request represents too large a measure of damages does not convince me that Kansas is entitled to no interest for damages prior to 1985. Nothing in our Kansas III opinion compels such a result. Opinion of STEVENS, J. In my view, the proper measure of damages on which Colorado owes Kansas interest is the entire amount attributable to the time that Colorado knew, or should have known, that it was violating the compact. That date is 1969-the date that the Special Master initially chose and that we implicitly accepted as appropriate in Kansas III. Choosing 1969 as the initial date for the damages period not only has the benefit of respecting our affirmation of the methodology in the Special Master's Third Report, it also results in a total damages sum that is less than the $38 million the Special Master originally awarded. Accordingly, I would sustain Kansas' second objection to the Special Master's Report, but only insofar as it applies to post-1968 damages. Syllabus KP PERMANENT MAKE-UP, INC. v. LASTING CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE NINTH CIRCUIT No. 03-409. Argued October 5, 2004-Decided December 8, 2004 Petitioner KP Permanent Make-Up, Inc., and respondents (collectively Lasting) all use the term "micro color" (as one word or two, singular or plural) in marketing permanent cosmetic makeup. The Court accepts KP's claim that it has used the single-word version since 1990 or 1991. In 1992, Lasting registered a trademark that included the words "Micro Colors" under 15 U. S. C. § 1051, and, in 1999, the registration became incontestable, § 1065. When Lasting demanded that KP stop using the word "microcolor," KP sued for declaratory relief. Lasting counterclaimed, alleging, inter alia, that KP had infringed Lasting's trademark. KP responded by asserting the statutory affirmative defense of fair use, §1115(b)(4). Finding that Lasting conceded that KP used "microcolor" only to describe its goods and not as a mark, the District Court held that KP was acting fairly and in good faith because KP undisputedly had employed the term continuously from before Lasting adopted its mark. Without enquiring whether the practice was likely to cause consumer confusion, the court concluded that KP had made out its affirmative defense under § 1115(b)(4) and entered summary judgment for KP on Lasting's infringement claim. Reversing, the Ninth Circuit ruled that the District Court erred in addressing the fair use defense without delving into the matter of possible consumer confusion about the origin of KP's goods. The court did not pointedly address the burden of proof, but appears to have placed it on KP to show the absence of such confusion. Held: A party raising the statutory affirmative defense of fair use to a claim of trademark infringement does not have a burden to negate any likelihood that the practice complained of will confuse consumers about the origin of the goods or services affected. Pp. 117–124. (a) Although § 1115(b) makes an incontestable registration "conclusive evidence. . . of the registrant's exclusive right to use the . . . mark,” it also subjects a plaintiff's success to "proof of infringement as defined in section 1114." Section 1114(1) in turn requires a showing that the defendant's actual practice is "likely to cause confusion, or to cause mistake, or to deceive" consumers about the origin of the goods or services in question, see, e. g., Two Pesos, Inc. v. Taco Cabana, Inc., 505 U. S. |