More than 5,000 police officers are claiming compensation from the government for trauma experienced while serving in Northern Ireland during the Troubles.
In what is the biggest group action to come before a Northern Irish court, the officers - both serving and retired - are suing the chief constable and the Police Board, alleging they failed to tackle injuries such as post-traumatic stress disorder, anxiety and depression.
The action is not about actual injuries sustained, as the officers accept that by joining the police force they knew the possible situations they could face.
However, they allege the authorities failed to put a strategy into place to deal with psychiatric and psychological consequences.
The case, which began today, is expected to last four months and if successful the government may have to pay as much as £100 million in damages.