BOSTON (AP) – Smokers of so-called light cigarettes can pursue a class-action lawsuit against Philip Morris USA based on the claim that the tobacco giant advertised Marlboro Lights as less harmful than other brands, Massachusetts’ highest court ruled Friday.

The Supreme Judicial Court’s 4-3 decision marks the first time any state’s high court has allowed smokers to proceed with a class action against the industry over the marketing of light cigarettes. Class-action status means anyone with a similar complaint against Philip Morris can join the suit and could be included in any monetary judgment against the company.

It is “the most important decision in tobacco litigation in many a year” because 90 percent of the cigarettes sold in the country are marketed as “light,” said Steve Sheller, one of the attorneys for the plaintiffs who is also pursuing other similar class-action lawsuits.

The high court’s ruling dealt with the question of whether smokers who brought suit under the state’s consumer protection laws represent a class of plaintiffs who can sue Philip Morris over its marketing of Marlboro Lights.

“We conclude that a class action is not only an appropriate method to resolve the plaintiff’s allegations, but, pragmatically, the only method whereby purchasers of Marlboro Lights in Massachusetts can seek redress for the alleged deception,” Justice John M. Greaney wrote in the majority opinion.

The case now returns to Superior Court, where it will proceed toward a trial.

Todd S. Heyman, an attorney for Lori Aspinall and Thomas Geanacopoulos, the two smokers who filed the lawsuit in 1998, praised the ruling.

Philip Morris said the ruling is limited to Massachusetts and will have no bearing on similar cases elsewhere. The company had argued that proof of damage was needed for each individual smoker.

“Philip Morris USA believes that plaintiffs will not be able to prove at trial that there was any deceptive conduct … or that consumers were actually damaged as a result of the purchases,” said Philip Morris USA attorney William S. Ohlemeyer.

He also said all cigarettes have the same health warnings. Many smokers continue to smoke Marlboro Lights despite knowing they may not be getting lower tar, Ohlemeyer said.

A similar lawsuit against Philip Morris in Illinois resulted in a $10.1 billion verdict last year, but the question of the class status of those plaintiffs is pending in the Illinois Supreme Court.

Aspinall and Geanacopoulos claimed in their lawsuit that the nation’s biggest tobacco retailer deceived smokers into thinking Marlboro Lights were better for them than regular Marlboros.

A Superior Court judge gave them the go-ahead to make it a class-action suit. Philip Morris appealed, and a higher court decertified the class, ruling that the plaintiffs did not have enough in common to join in the suit. That ruling was appealed to the SJC, which heard arguments in April.

Marlboro Lights, which went on the market in 1971, are the nation’s most popular cigarettes, according to Philip Morris. The company removed the phrase “lowered tar and nicotine” from packs of Marlboro Lights last year.

Similar lawsuits over light cigarettes have been filed in at least 11 states. Others were decided by lower courts or are still under review.

Mark Gottlieb, senior attorney with the Tobacco Products Liability Project at Northeastern University, said that while the ruling will have a direct impact only on the Massachusetts lawsuit, it will likely influence courts elsewhere that have not yet decided the issue of class certification.

“This is a pivotal decision,” he said. “Had it gone the other way, I think it would similarly have been quite influential.”

Shares in Altria Group Inc., the parent company of Philip Morris, were down 53 cents to $46.85 in afternoon trading Friday on the New York Stock Exchange.

AP-ES-08-13-04 1623EDT