A federal judge denied class certification for plaintiffs who claimed that McDonald’s engaged in a long-running marketing scheme designed to mislead consumers into believing that daily consumption of its food would not result in adverse health effects.

U.S. District Court Judge Donald C. Pogue found that the plaintiffs failed to provide sufficient evidence to establish a class of plaintiffs with identical claims and that too many individual, factual questions were present to create a class.

The complaint was filed in 2002 by four children and their parents, who alleged that between 1985 and 2002, the minors became obese and suffered other adverse health effects, such as coronary heart disease, pediatric diabetes, and high blood pressure after consuming McDonald’s foods. The suit argued that McDonald’s engaged in a deceptive marketing scheme to mislead consumers into falsely believing that its food products – such as Filet-O-Fish, hamburgers and french fries, and Chicken McNuggets – were healthy.

Over the last eight years, the case has bounced from state to federal court and the parties have engaged in various pretrial motions.

In the latest ruling, the court refused to grant class certification or to certify an issue class to determine whether the defendant was liable. The plaintiffs’ claims would require “individualized inquiries…to determine whether each plaintiff suffered injury as a result of being deceived by [McDonald’s] allegedly misleading representations,” Judge Pogue wrote. “Because plaintiffs have failed to present specific evidence of a sufficiently numerous class of individuals who were both exposed to [McDonald’s] allegedly deceptive marketing scheme and have subsequently suffered from the same adverse medical conditions as those alleged by plaintiffs to have been the result of their exposure,” he ruled that class certification was inappropriate.

The presence of medical conditions such as obesity or high cholesterol “depends heavily on a range of factors unique to each individual,” the court said. Despite the plaintiffs’ argument that a general causal link exists between consumption of McDonald’s products – because they are high in fat, salt, and cholesterol, and low in fiber and certain vitamins – the court said individualized inquiries were required to rule out various other factors, such as the level of regular physical activity in which each plaintiff engaged.

Judge Pogue also denied issue certification for the plaintiffs, ruling that they had failed to provide specific evidence that other plaintiffs with similar injuries existed.

To read the motion denying class certification in Pelman v. McDonald’s Corp., click here.

Why it matters: The ruling is a blow to the plaintiffs and a victory for McDonald’s. Even with a small number of plaintiffs, the suit faces an uphill battle as indicated by Judge Pogue in his decision. Each plaintiff will have to prove the causal nexus between eating Chicken McNuggets and his or her resulting health issue, exclusive of various other possible factors that contributed to their alleged health related claims.