NEW YORK (CNN) - The Illinois Supreme Court on Thursday tossed out a $10.1 billion verdict against Philip Morris USA in which the company was accused of fooling customers into thinking "light" cigarettes are safer than regular cigarettes.

The much-anticipated ruling sent shares of Philip Morris parent Altria Group Inc. (up $3.45 to $77.18, Research) up about 5 percent in heavy trading on the New York Stock Exchange. The shares hit a 52-week high during the session.

In a summary of its decision, the Supreme Court reversed the verdict and ordered a lower court to dismiss its 2003 judgment, stating that the Federal Trade Commission "had specifically authorized tobacco companies to characterize their products as 'light' or 'low tar and nicotine'."

George Zelcs, an attorney for plaintiff Sharon Jones, told CNN, "This is not a decision that's based upon the factual record of this case, but rather the notion that the FTC has pre-empted this issue."

Zelcs added that there is a "high probability" that the case will be appealed to the U.S. Supreme Court.

Philip Morris USA, a unit of New York-based Altria, issued a brief statement saying, "Philip Morris USA is gratified by today's Illinois Supreme Court decision in the Price case. The company will have no further comment on today's decision."

The case has been closely watched not just because of the size of the ruling, but because it is one of the legal hurdles Altria management has said needs to be cleared before it executes plans to spin its Kraft Foods Inc. (down $0.58 to $28.36, Research) unit from its tobacco businesses.

"Even though this was a well-anticipated reversal...the market still has reacted positively to the ruling in pushing up tobacco stocks because this removes yet another legal impediment to the survival of the industry," Tim Ghriskey, chief investment officer for Solaris Asset Management told Reuters news service.

The class action case was originally filed in Illinois' Madison County in 2000 before a state circuit judge without a jury.

Lead plaintiffs Jones and Michael Fruth said they were both smokers who had switched to "light" or "low tar" cigarettes because tobacco companies had marketed them as being safer than regular cigarettes.

In 2003 the judge awarded 1.1 million members of the suit $10.1 billion in damages, attorney fees and interest after finding that Philip Morris intentionally and falsely misrepresented "light" cigarettes as less dangerous than regular cigarettes.

Reuters reported that the Supreme Court took the unusual step of bypassing the appellate court and hearing the case on appeal directly from the trial court.

Philip Morris had argued that the case should never have been certified as a class but should have required each individual smoker to prove their case separately.

--From CNN Business News Assignment Editor Tom Ziegler

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