U.S. trademark law
Under the doctrine of nominative fair use, the defendant uses the plaintiff’s trademark to specifically identify the plaintiff for certain purposes — such as comparative advertising or advertising repair services or replacement parts for the plaintiff’s goods. 
The nominative fair use defense is appropriate "where a defendant has used the plaintiff's mark to describe the plaintiff's product, even if the defendant's ultimate goal is to describe his own product." It “acknowledges that ‘it is often virtually impossible to refer to a particular product for purposes of comparison, criticism, point of reference or any other such purpose without using the mark.”
|“||The court looks at three factors in determining whether a defendant is entitled to the nominative fair use defense (1) the product must not be readily identifiable without use of the mark; (2) only so much of the mark may be used as is reasonably necessary to identify the product; and (3) the user must do nothing that would, in conjunction with the mark, suggest sponsorship or endorsement by the trademark holder.||”|
- "A defendant may use a plaintiff's trademark to identify the plaintiff's goods so long as there is no likelihood of confusion about the source of defendant's product or the mark-holder's sponsorship or affiliation. Merck & Co. v. Mediplan Health Consulting, Inc., 425 F.Supp.2d 402, 413 (S.D.N.Y. 2006).
- Cairns v. Franklin Mint Co., 292 F.3d 1139, 1151 (9th Cir. 2002).
- Brother Records, Inc. v. Jardine, 318 F.3d 900, 908 (9th Cir. 2003) (citation omitted).
- Horphag Res. Ltd. v. Pelligrini, 337 F.3d 1036, 1041 (9th Cir. 2003).