## Facts

- McNeil-PPC, Inc., a leading seller of dental floss and interdental cleaners, sued Pfizer Inc. over a national advertising campaign for Listerine Antiseptic Mouthrinse.
- Pfizer’s campaign (print, hang tags, and television) compared Listerine to floss, including visuals of a Listerine bottle balanced against floss and a commercial depicting blue liquid tracking a strand of floss and moving between teeth.
- The television advertising repeatedly stated: “Listerine’s as effective as floss at fighting plaque and gingivitis. Clinical studies prove it.”
- The ads also included a disclaimer that “there’s no replacement for flossing,” but the court found the equivalence message predominated.
- Pfizer relied on two clinical studies comparing Listerine and dental floss for subjects with mild to moderate gingivitis; the studies’ authors noted that results could be affected by poor floss compliance by participants assigned to floss.
- McNeil alleged (1) literal falsity because the cited studies did not prove Listerine is as effective as floss and (2) misleading implied messaging that Listerine can replace floss.
- McNeil offered a consumer survey indicating about 30% of consumers took away the message that floss can be replaced with Listerine.
- McNeil also presented evidence that floss provides benefits not addressed by the studies or provided by Listerine (e.g., removal of food particles and mechanical disruption of plaque between teeth).

## Issues

1. Whether Pfizer’s “clinical studies prove” and “as effective as floss” claims were literally false under § 43(a) of the Lanham Act.
2. Whether the campaign, even if not literally false, was misleading by implying Listerine can substitute for floss.
3. Whether McNeil satisfied the requirements for a preliminary injunction (likelihood of success, irreparable harm, balance of hardships, and public interest).

## Decision

- The court granted McNeil’s motion for a preliminary injunction.
- The court held Pfizer’s challenged advertising was false and misleading under the Lanham Act.
- The court enjoined Pfizer from continuing to disseminate the challenged “as effective as floss” claims and related messaging conveying substitution.

## Legal Principles

- A Lanham Act false advertising claim may be proven by showing either (a) literal falsity or (b) that an ad, though literally true or ambiguous, is misleading and likely to deceive a substantial segment of the audience.
- If an advertisement is literally false, injunctive relief may be granted without proof of consumer reaction; if the claim is misleading, extrinsic evidence such as consumer surveys is typically required.
- “Establishment claims” (e.g., “clinical studies prove”) are literally false when the cited studies do not, in fact, establish the proposition asserted.
- Advertising must be assessed in context, including visuals and repeated messages; a brief disclaimer does not cure a dominant misleading net impression.
- For preliminary injunctions in false advertising cases, likelihood of success and likely consumer deception may support a finding of irreparable harm; courts also weigh hardships and the public interest in truthful health-related advertising.

## Conclusion

The court enjoined Pfizer’s Listerine campaign because Pfizer overstated what its clinical studies demonstrated by claiming proven equivalence to floss and, through the overall presentation, conveyed a misleading substitution message despite a limited disclaimer.


McNeil-PPC, Inc. v. Pfizer Inc., 351 F. Supp. 2d 226 (S.D.N.Y. 2005)