In the past decade 250 'lifers' sentenced for terrorist murders have been released, together with a further 70 non-terrorists.
Under the terms of their release they can be arrested and recalled to prison without notice and without judicial proceedings.
This threat of instant recall acts as a powerful deterrent, and the authorities are satisfied that none of those freed have become re-involved in terrorist activity.
The 250 are roughly half republicans and half loyalists. There are 300 lifers still inside. The release scheme, which is markedly more liberal than policies operating in Britain or the Irish Republic, means many lifers have been set free after serving 11 or 12 years.
A number of criteria are considered, including the nature of the original offence and the prisoner's behaviour in jail. The crucial calculation, however, is whether they are likely to re-offend.
There have recently been complaints that a change in the approach of the authorities means ministers are insisting on longer terms for killing soldiers. In practice this would mean republicans serving longer terms than loyalists.
Welfare workers say most of the released lifers have difficulties in re-adjusting to the outside world, but say a majority of them become involved in community work. Many of them are now active in youth work, for example in working with joyriders.
One worker said: 'They're not like fixed-term prisoners, a lot of whom just go back to violence. Some of them develop businesses, some get involved in useful community work, some - both Protestants and Catholics - get into Christian work. All the evidence is that released lifers are spending their time atoning.'Reuse content