Life sentence prisoners released in 2016 served an average 22 years in custody, an increase of four-and-a-half years on 2015.

It is the second year in the history of the State that the average time served in prison by inmates sentenced to life has been 22 years, with the same average recorded in 2012.

The average time served in custody by lifers has increased significantly since the 1970s and 1980s when inmates could expect to spend about 7-and-a-half years in jail.

Information from the Irish Prison Service shows that in 2016 seven life sentence prisoners were released into the community after an average length of 22 years.

When life sentence prisoners are released they continue to serve their sentences in the community under strict conditions. While in the community, a life sentence prsoner will be on reviewable temporary release.

On December 31, 2016, there were 352 prisoners in custody serving life sentences with a further 83 prisoners serving life sentences in the community on reviewable release. Four life sentenced prisoners were recalled to prison during the year.

Dr Diarmuid Griffin from the NUI Galway School of Law has conducted research into life sentences in Ireland.He said the average time served for life sentence prisoners released between 1975 and 1984 was 7.5 years; from 1985 to 1994 it was 12 years, increasing to 14 years from 1995 to 2004 and 18 years from 2005 to 2014.

“If you look at what has happened in the 30-40 year time period, there doesn’t seem to be any indication of a reversal of the trend for longer sentences,” he said.

He added that now the average has reached 22 years, “it’s important that there is some constraint placed on it and that we have some consistency… we need to maintain a more consistent approach”.

Dr Griffin said it is likely that the political and discretionary nature of parole, whereby the Minister for Justice approves the release from custody of a life sentence prisoner on the recommendation of the parole board, has possibly facilitated such significant increases in time served.

Fianna Fáil justice spokesman Jim O’Callaghan, who sponsored the Parole Bill 2016, said the parole board should be put on a statutory basis so the public would be aware of the criteria involved when it is considering an application. “Nowhere is there a law setting out the criteria on which parole is granted,” he said.

On life sentences, he said seven or eight years served in prison was too short. “If someone gets a life sentence they have to serve a significant period of time,” he said. “If you get life you should have to serve at least 12 years.”