John Gilligan has lost a Supreme Court challenge against his sentence on the eve of his release.

The convicted drug trafficker took issue with the mandatory nature of the consecutive sentences he received for offences he committed as an inmate.

While serving a 20 year term for drug offences, he was given a further two years for assaulting a prison officer and another six months on top of that for possessing a mobile phone.

The case won't have an impact on Gilligan (61) walking free from Portlaoise prison after midnight tonight.

Michael O'Toole, crime correspondent for the Irish Daily Star, spoke to Newstalk's Breakfast about Gilligan's release earlier:

John Gilligan was found not guilty of the murder of journalist Veronica Guerin in 2001.

File picture of John Gilligan above