A Dublin teenager, whose six year prison sentence for attempted murder was deferred last month, will go to jail on Friday following a failed application for continuing bail.

Tadhg Costello, 19, of Richmond Hill, Monkstown, was sentenced on 7 March to six years imprisonment with the final three suspended for the attempted murder of Josh Leahy at Johnson's Court in Dublin city on 31 May 2012..

Costello had originally pleaded not guilty to the attempted murder charge but changed his plea to guilty following a ruling by trial judge Mr Justice Paul Butler that the teenager's garda interview recordings were admissible as evidence.

Mr Justice Butler deferred the committal order on foot of a Supreme Court ruling the previous day, flagged by counsel, which quashed an attempted rape conviction on grounds that suspects who request a lawyer cannot be questioned by gardaí until they get legal advice.

In the Court of Criminal Appeal today, Mr Justice William McKechnie presiding, rejected arguments put forward by lawyers for Costello that the Supreme Court ruling had anything to do with the teenager's application.

The issue which arose during Costello's trial, Mr Justic McKechnie said, was whether he or his mother had been informed of their right to consult a solicitor.

However, in the Supreme Court's ruling, Mr Justice McKechnie said, the applicant involved had activated his right to have access to a lawyer but "before the solicitor arrived, interviewing by gardaí had continued".

Mr Justice McKechnie, along with Mr Justice Michael Moriarty and Ms Justice Deirdre Murphy, said that there was no question of the criteria in the Supreme Court's ruling being satisfied and therefore the application must be refused.

The trial judge relied on evidence from a Garda Beakey, Mr Justice McKechnie said, that he advised Costello's mother of their right of access to a solicitor and that he had done so in a telephone call to her. It was recorded on the custody record, he said.

The second basis for Mr Justice Butler's decision was that Costello and his mother had attended a garda station in June 2011 and further in November of that year, where on either one or both occasions they were informed of their right and should have known of this right.

The trial judge's decision was "unreviewable" by the Court of Criminal Appeal because it was formed from evidence of a credible nature based on a material fact, Mr Justice McKechnie said.

Costello is due to hand himself in to Dún Laoghaire Garda Station on Friday where he will be taken into custody to begin serving his sentence.

The Central Criminal Court heard that Costello had admitted in garda interviews that he carried a knife at all times and had sharpened it.

He also told gardaí he knew the victim was Mr Leahy and said his intention was to kill.

Garda Philip Gleeson agreed with counsel for the DPP, Paul Burns SC, that he showed no remorse in his interviews.

A probation report put Costello at moderate risk of reoffending within the next 12 months.

Josh Leahy, who is now 19, was stabbed six times in the back in a row between two groups of youth, which was captured on CCTV.

The Ranelagh teen suffered a collapsed lung and had a chest drain inserted at St. James's Hospital.

In a victim impact report read to the court on behalf of Mr Leahy, the victim said he had nightmares and still had some pain from his injuries.

In sentencing, Mr Justice Butler said that it was "a very serious offence" and Costello had stabbed Mr Leahy at least six times with an intent to kill but had no immediate remorse.

The judge noted Costello, who lives with his mother in Monkstown, had no previous convictions and he was a minor at the time the offence was committed.

He also noted that there was legal argument over the admissibility of his interviews and Costello immediately pleaded guilty to the attempted murder charge after they were allowed.

Mr Justice Butler said the case was tragic, not just for the Leahy family and said he was much impressed by the support given by the accused's mother.

"The attack has had and continues to have a severe impact on Mr Leahy who I note is in court today," he said.