With the US Supreme Court ruling on Monday that tobacco firms can be sued under state law for deceptive advertising of "light" cigarettes, nearly 40 lawsuits around the country will be affected, claiming billions of dollars in damages.

In a 5-to-4 decision, high court ruled against Altria Group Inc.'s Philip Morris USA unit, and held the Federal Cigarette Labeling and Advertising Act does not bar or preempt such state court lawsuits.

In the class-action lawsuit, three smokers from Maine sued Altria and its Philip Morris USA unit, alleging fraud under Maine's Unfair Trade Practices Act, and saying they had suffered due to the 'false statements' of the companies.

The plaintiffs sought compensation for economic rather than medical harm. They claimed that they had overpaid for cigarettes based on deceptive advertisements suggesting that "light" cigarettes were safer than regular ones.

The lawsuit argues that cigarettes like Marlboro and Cambridge Lights are deceptively designed and marketed, and that the amounts of tar and nicotine consumed by a smoker of those brands and a smoker of regular cigarettes is the same.

Justice Clarence Thomas wrote: "The alleged misrepresentation here - that 'light' and 'low tar' cigarettes are not as healthy as advertised - is actionable only because of the effect that smoking light and low-tar cigarettes had" on the plaintiffs' health.

David C. Frederick, who represented the plaintiffs, said the tobacco industry should view the court's decision as an opportunity, and added: "It would be appropriate for the tobacco companies to take a very hard look at how they market their products, because they have for decades been making deceptive claims about their products."