The Government is considering a system under which prisoners serving long sentences would be released earlier than at present.
At the moment those serving life have their sentences reviewed after seven years, but many wait much longer before engaging with the Parole Board, which can recommend early release.
Minister for Justice Alan Shatter is considering lowering this to five years.
Those serving life sentences would also be more actively encouraged to engage with the Parole Board.
This would be done with a view to encouraging them into education and rehabilitation, with their possible early release being reviewed regularly.
If the measures worked, some prisoners would be released earlier than at present.
Prisoners serving life sentences have exceeded 300 for the first time, having increased from 221 in 2005. The prison population is about 4,400.
Lifers are held indefinitely, until their release is sanctioned by the Minister for Justice, advised by the Parole Board.
A life sentence is mandatory for murder convictions and can be imposed for some other crimes, including rape.
Life prisoners serve an average of 17 years, up from 12 years two decades ago, when some served just seven years.
Chairman of the Parole Board John Costello has said prisoners serving long life terms become institutionalised, making their release and reintegration very difficult.
