The U.S. Supreme Court ruled Monday that lawsuits may proceed against tobacco companies for allegedly deceptive marketing of "light" cigarettes.

In a 5-4 split won by the court's liberals, the court said smokers may use state consumer protection laws to sue cigarette makers for the way they promote "light" and "low tar" brands.

The decision was at odds with recent anti-consumer rulings that limited state regulation of business in favour of federal power.

The tobacco companies argued that the lawsuits are barred by the federal cigarette labelling law, which forbids states from regulating any aspect of cigarette advertising that involves smoking and health.

Justice John Paul Stevens, however, said in his majority opinion that the labelling law does not shield the companies from state laws against deceptive practices.

People suing the cigarette makers still must prove that the use of 'light' and 'lowered tar' labels actually violate the state anti-fraud laws, but those lawsuits may go forward, Stevens said.

Ideological split seen

He was joined by the other liberal justices, Stephen Breyer, Ruth Bader Ginsburg and David Souter, as well as Justice Anthony Kennedy, whose vote often decides cases where there is an ideological division.

The conservative justices, Chief Justice John Roberts and justices Samuel Alito, Antonin Scalia and Clarence Thomas, dissented.

Three Maine residents sued Altria Group Inc. and its Philip Morris USA Inc. subsidiary under the state's law against unfair marketing practices. The class-action claim represents all smokers of Marlboro Lights or Cambridge Lights cigarettes, both made by Philip Morris.

The lawsuit argues that the company knew for decades that smokers of light cigarettes compensate for the lower levels of tar and nicotine by taking longer puffs and compensating in other ways.

A federal district court threw out the lawsuit, but the 1st U.S. Circuit Court of Appeals said it could go forward.

The companies were hoping that the court would send a clear message that would essentially end dozens of such lawsuits that have been filed around the country.

The case is Altria Group Inc. v. Good, 07-562.