The five-four ruling, which opens Altria's Philip Morris and its peers to a spate of litigation, affirms an appellate-court decision that federal cigarette labelling laws preventing states from enacting additional smoking regulations was not a reason to prevent a lawsuit from proceeding in a Maine district court.

Citing the Maine Unfair Trade Practices Act, a group of longterm smokers claimed they were misled by Philip Morris' efforts to suggest that Marlboro Lights and Cambridge Lights were less harmful than regular cigarettes because they had “l(fā)owered tar and nicotine”.

While the plaintiffs acknowledged that the “l(fā)ight” brands did indeed have less tar and nicotine, they argued the company knew that smokers compensated for the decreased potency by holding smoke in their lungs longer or covering filter ventilation holes with their lips or fingers.