The Lapp test is the standard used to determine whether a likelihood of confusion exists between two trademarks. Under the Lanham Act, liability for trademark infringement is essentially based on a finding that the use of one trademark causes a likelihood of confusion with another previously established trademark. A likelihood of confusion exists when an allegedly infringing trademark is likely to cause an appreciable number of reasonably prudent purchasers to be confused as to the source or origin of the products or services it is used to identify.
The Lapp test is a multi-factored test used to establish the existence of a likelihood of confusion. The Lapp factors include: (1) similarity of the marks; (2) strength of plaintiff's mark; (3) sophistication of consumers when making a purchase; (4) intent of defendant in adopting the mark; (5) evidence of actual confusion (or lack thereof); (6) similarity of marketing and advertising channels; (7) extent to which the targets of the parties’ sales efforts are the same; (8) product similarity; identity/function/use; and (9) other factors suggesting that consumers might expect the prior owner to manufacture both products, or expect the prior owner to manufacture a product in defendants market , or expect the prior owner is likely to expand into defendant’s market. See Interpace Corp. v. Lapp, Inc., 721 F.2d 460 (3d Cir. 1983).
The Lapp test is a non-exhaustive list of factors relevant to assessing the likelihood of confusion. Not all factors will be relevant in all cases, and the different factors may properly be accorded different weights depending on the circumstances of each particular case. No single factor is dispositive and a finding of a likelihood of confusion does not require a positive finding on a majority of the factors listed. The Lapp factors are intended as a guide; a court is free to consider any other relevant factors in determining whether a likelihood of confusion exists. See A&H Sportswear, Inc. v. Victoria's Secret Stores, Inc., 237 F.3d 198 (3rd Cir. 2000).