Pleural plaques are small areas of thickening on the membrane covering the lungs and are caused by the inhalation of asbestos fibres.
Although they are harmless and, in almost all cases, symptomless, they show that the person has been exposed to asbestos fibres and so indicate an increased risk of that person developing an asbestos-related condition in the future. Many people diagnosed with pleural plaques become severely anxious about this risk.
For over twenty years, such individuals were able to claim damages from employers who negligently exposed them to asbestos at work. But in October 2007, the House of Lords (now the Supreme Court) found there was no legal basis for such claims.
The Law Lords held that it is a fundamental requirement of a negligence action that the negligence causes injury and the claimant suffers damage as a result. According to current medical knowledge, however, plaques are harmless, therefore there is no injury. Without physical injury, the risk of contracting a future disease and the claimant's anxiety are not actionable claims.
In response, the Scottish Parliament passed the Damages (Asbestos-Related Conditions) (Scotland) Act, which effectively reversed the House of Lords decision as far as Scotland was concerned.
The Act, which came into force in June 2009, states that any rule of law that says asbestos-related pleural plaques do not constitute actionable harm "ceases to apply to the extent it has that effect".
In April 2009 a group of insurers including Aviva, AXA Insurance, RSA and Zurich applied for judicial review of the Act but their challenge was dismissed by the Scottish Court of Session in January 2010.
Insurers appealed, arguing that the Act was irrational, disproportionate and contravened the European Convention on Human Rights.
The Convention protects a person's right to peaceful enjoyment of their possessions and provides that no one shall be deprived of their possessions except in the public interest.
Insurers argued that the Act was an interference with their assets and capital reserves that could not be justified on the grounds of public interest. It imposed a liability on employers (and so on their insurers) that would not exist but for the Act. Since, under the Scotland Act 1998, the Scottish Parliament is unable to pass laws that are incompatible with the Convention, the Act was unlawful.
The Inner House of the Court of Session disagreed. In a detailed judgment published on 12th April, it said it did not accept that irrationality was a proper ground for reviewing an Act passed by the Scottish Parliament. But even if it were, insurers had failed to show the Act was irrational or disproportionate.
In the court's view, Parliament had been entitled to take into account the fact that insurers had been paying pleural plaques claims for many years. The intention behind the Act was clearly to ensure that this compensation would continue.
As for the Convention, the court accepted the Act was an interference with insurers' rights. Employers' liability insurance is compulsory so it was inevitable that it would be insurers who ended up paying these claims. But Parliament had chosen to take action to rectify what it considered to be a social injustice. In doing so, the court held it had pursued a legitimate aim in the public interest.
"Criticisms may no doubt be made of that decision," the judgment states. "But the existence of grounds of criticism of their approach does not, of course, render the legislators' decision invalid. Assessing the validity and weight of such criticisms is essentially a matter of governmental and political judgment."
The Association of British Insurers has commented that the decision ignores overwhelming medical evidence that pleural plaques do not impact on health. It confirms that the insurers concerned will be appealing against the judgment to the Supreme Court.
The ruling will not have an impact in England and Wales, where in February 2010, the Labour Government decided against passing legislation to change the law on pleural plaques. Instead it opted for a package of other measures intended to increase understanding of pleural plaques and improve the claims process for mesothelioma victims generally.
