London (CNN) -- A landmark ruling in the UK Supreme Court has cleared the way for thousands of mesothelioma victims and their families to make insurance claims.
The court ruled Wednesday that the liability for insurers was incurred at the time a worker was exposed to asbestos, rather than at the time when the disease first appeared.
The decision overturned an appeals court ruling which had meant many families would not have been able to claim compensation.
Mesothelioma can develop decades after exposure to asbestos fibers.
The case was brought by a number of insurers who argued that liability should only be incurred when the symptoms of asbestos-related illness develop.
But the court said there was a close link between employment and the exposure that led to the illness, and that upholding the appeals court ruling could mean a potential gap in insurance coverage for workers, especially those no longer employed by the same firm.
Lawyer Helen Ashton, who represented a woman whose father died of asbestos-related disease, said in a statement that she was delighted by the Supreme Court's ruling.
"This long awaited judgment provides clarity, consistency and comfort for mesothelioma victims and their families," said Ashton, of the law firm Irwin Mitchell.
"As well as the people currently directly affected by asbestos related disease, this judgment means that the thousands of people who are yet to be given the devastating news that they have the deadly illness will at least know that their families can get access to justice and receive the financial security they need."
Asbestos-related disease is one of the biggest workplace killers in Britain, she said, leading to more than 5,000 deaths each year.
The number of people affected is still rising, she said, and because of the time it takes for the disease to develop, the number of deaths in the United Kingdom is expected to peak in 2015.
Ashton said her client, Ruth Durham, had pursued the case in memory of her father, Leslie Screach, and was very pleased by the judgment.
Screach died of mesothelioma in 2003 after being exposed to asbestos fibers from 1963 to 1968 while working as a paint sprayer in London, the lawyer's statement said.
"I was determined to see this through with a positive outcome for all those who, like my dad, suffered so terribly because of someone else's negligence," Durham said.
The Association of British Insurers, an industry body, said it welcomed the ruling -- and that only a small group of insurers had sought a different outcome.
"We have always opposed the attempt to change the basis on which mesothelioma claims should be paid, as argued by those who brought this litigation," said Nick Starling of the ABI.
"Today's ruling by the Supreme Court has confirmed what most in the industry have always understood -- that the insurer on cover when the claimant was exposed to asbestos should pay the claim, rather than the insurer on cover when the mesothelioma develops."
Asbestos was once widely used as a fireproofing material and was included in roof shingles and siding for decades. Though now banned in most Western countries, asbestos is still used in developing countries, mainly in China and India.
Exposure to its tiny fibers, particularly over a period of time, can lead to asbestos-related diseases that include lung cancer, asbestosis and mesothelioma, according to the U.S. National Institutes for Health.