In Al Haj v. Pfizer, the plaintiffs brought a putative class action alleging that Pfizer misled consumers about the marketing of its "Maximum Strength" Robitussin. According to the plaintiffs, the higher-priced "Maximum Strength" version of the cough syrup does not have a higher concentration of active ingredients than the regular strength version.

If "Maximum Strength" does not have a higher amount of active ingredients, how can it be marketed this way?  According to Pfizer, it's because the recommended adult dosage for the "Maximum Strength" version is double the recommended adult dosage of the regular strength version.  Because of the higher dosage amount, it results in the "Maximum Strength" version being stronger. 

Pfizer moved to dismiss on various grounds, including that the "Maximum Strength" label is not deceptive because "one dose of Maximum Strength Robitussin is stronger -- i.e., contains more medicine -- than one dose of Regular Strength Robitussin."  Denying Pfizer's motion, the United States District Court for the Northern District of Illinois wrote, "it is at least plausible that a reasonable consumer would construe an assertion about a product's relative strength ('Regular' vs. 'Maximum') as one that concerns the product's relative potency and therefore that depends on the concentration of the product's active ingredients, not the total quantity consumed." 

Pfizer also argued that "Maximum Strength" isn't misleading because the product labels "explicitly list the dosage and the amount of active ingredients per dosage."  The court rejected this argument as well, writing, "Absent some kind of context clue . . . it is not reasonable to expect a consumer to cross-check a product's ingredient list against another product's list and then perform arithmetic to make sure she is comparing equivalent dosage volumes, all to ensure that the product she intends to purchase has the qualities it purports to have."