The California Supreme Court decided unanimously Thursday that smokers may sue cigarette makers once they develop a disease such as lung cancer, even if they suffered different smoking-related ailments years earlier.

The decision is likely to keep alive lawsuits that might have otherwise been thrown out because of expired legal deadlines, and to permit new suits to be filed.

In the case before the court, a former smoker was diagnosed with chronic obstructive pulmonary disease in 1989 and a couple of years later with periodontal disease, both attributable to smoking Lucky Strike or other brands. But she did not sue the tobacco industry until she was diagnosed with lung cancer in 2003.

Cigarette makers argued that her suit should be dismissed because the timetable for suing began when she first discovered that smoking had injured her in 1989.

The state high court, in a ruling written by Justice Joyce L. Kennard, concluded that an earlier disease does not trigger the legal deadline for filing suit if the injury was “separate and distinct” from the later ailment.

“We hold that two physical injuries — both caused by the same tobacco use over the same period of time — can, in some circumstances, be considered ‘qualitatively different’” for determining when the clock begins ticking on legal deadlines, Kennard wrote.

“Although we are disappointed with the decision, the California Supreme Court made it clear that it was not addressing the merits of this case or any case,” the statement said. “Rather, the decision addresses a narrow technical point of law relating to the statute of limitations. The decision would be relevant only in a very small fraction of cases filed.”

Lloyd LeRoy, an attorney for the former smoker, called the ruling “extremely significant, particularly for tobacco litigation in California.”

Until Thursday’s ruling, smokers could not sue after getting lung cancer if their medical records showed that they were diagnosed with smoker’s cough or another smoking-related ailment years earlier, LeeRoy said. State legal deadlines give people two years to sue after discovering an injury.

“What this says is the courtroom door is open again,” LeeRoy said.

The smoker’s lawsuit is before the U.S. 9th Circuit Court of Appeals, which asked the state high court to clarify how legal deadlines should apply under California law.