Opinion of the Court
When, instead, the use is “at least in part” for “source identification”—when the defendant may be “trading on the good will of the trademark owner to market its own goods”—Rogers has no proper role. 221 F. Supp. 2d, at 414–415. And that is so, the court continued, even if the defendant is also “making an expressive comment,” including a parody of a different product. Id., at 415. The defendant is still “mak[ing] trademark use of another’s mark,” and must meet an infringement claim on the usual battleground of “likelihood of confusion.” Id., at 416.
That conclusion fits trademark law, and reflects its primary mission. From its definition of “trademark” onward, the Lanham Act views marks as source identifiers—as things that function to “indicate the source” of goods, and so to “distinguish” them from ones “manufactured or sold by others.” §1127; see supra, at 2–3. The cardinal sin under the law, as described earlier, is to undermine that function. See supra, at 3. It is to confuse consumers about source—to make (some of) them think that one producer’s products are another’s. And that kind of confusion is most likely to arise when someone uses another’s trademark as a trademark—meaning, again, as a source identifier—rather than for some other expressive function. To adapt one of the cases noted above: Suppose a filmmaker uses a Louis Vuitton suitcase to convey something about a character (he is the kind of person who wants to be seen with the product but doesn’t know how to pronounce its name). See supra, at 12. Now think about a different scenario: A luggage manufacturer uses an ever-so-slightly modified LV logo to make inroads in the suitcase market. The greater likelihood of confusion inheres in the latter use, because it is the one conveying information (or misinformation) about who is responsible for a product. That kind of use “implicate[s] the core concerns of trademark law” and creates “the paradigmatic infringement case.” G. Dinwoodie & M. Janis, Confusion Over Use: Contextualism in Trademark Law, 92
