Victims of a deadly disease caused by work-related asbestos exposure could miss out on compensation following a Court of Appeal ruling last week, campaign groups fear.

The Association of Personal Injury Lawyers (APIL) and trade union Unite branded the victory for insurance companies as ‘obscene’. The Trades Union Congress (TUC) expressed ‘grave concern at the continued uncertainty now faced by hundreds of people dying from asbestos exposure’.

Overturning a 2008 High Court ruling on mesothelioma, a cancer of the lung caused by asbestos exposure, the Court of Appeal decided that in some cases, employers’ liability insurance is triggered not by exposure to asbestos, but by the onset of symptoms.

APIL and Unite said this will leave some victims with no access to compensation because their employer may not have an effective insurance policy to meet the claim, and policy wordings may exclude previously eligible claimants.

Ian McFall, head of asbestos policy at national firm Thompsons, said: ‘This decision means some insurers are required to pay while others are not, depending on words such as "injury sustained" or "disease contracted" used in insurance contracts written decades ago.’

TUC general secretary Brendan Barber said: ‘This is the real compensation culture we face in this country. A culture where people can be killed as a result of their employer’s negligence, and then be denied the compensation they are entitled to.’

Unite joint general secretary Derek Simpson said: ‘Insurers banking premiums, and then escaping paying out compensation by relying on policy small print, is obscene.’

Nick Starling, director of general insurance and health at the Association of British Insurers, said it was ‘regrettable’ that a ‘small number’ of claimants may not get the compensation they could reasonably expect.

APIL spokesman Karl Tonks said: ‘Asbestos victims will effectively have to enter a lottery when trying to claim damages.’

The judgment is expected to be appealed.