Washington ? The Supreme Court cleared the way for a new era of tobacco litigation Monday, ruling that cigarette makers can be sued for deceiving smokers about the dangers of their highly popular “light” cigarettes.

The decision allows class-action lawsuits to proceed in several states and opens the door to new suits in most other states. Ten years ago, the tobacco industry agreed to a $206 billion settlement with 46 states to end lawsuits over the health care costs of smoking. But that agreement did not block new private lawsuits.

And this decision opens a new avenue of litigation over advertising claims the industry made for its low-tar and nicotine brands.

More than 45 million Americans are smokers, and nearly 85 percent of them buy cigarettes that, like Marlboro Lights, are sold as having lower tar and nicotine. Smokers switched to these “light” cigarettes starting in the 1970s, believing they were safer.

But when puffed by actual smokers — not machines — these light cigarettes yield about the same amount of smoke, tar and nicotine. Although the filters of these light cigarettes have air holes, studies found that smokers tend to cover these holes with their lips and take larger and deeper puffs to inhale more nicotine.

The Federal Trade Commission told the court that the tobacco industry has known for at least 30 years that light cigarettes are not safer. It also said the use of labels such as “light,” “ultra light” or “low tar” do little but fool smokers into thinking they face less of a health risk.