In a decision with immediate and serious implications for the operation of the criminal justice system the High Court has declared unconstitiutional the law governing the power of the courts to activate suspended sentences.

In a statement following the ruling the Department of Justice said it is examining the “consequences and implications” in consulation with the Attorney General.

Mr Justice Michael Moriarty declared key subsections of Section 99 of the Criminal Justice Act 2006, as amended under Acts of 2007 and 2009, unconstitutional on grounds including those allowed for significantly different treatment of persons before the law as far as their rights of appeal are concerned.

The fact there are weekly challenges arising from the operation of Section 99 shows that lay and professional persons involved in the criminal law arena “simply do not know at present where they stand”, he said.

Legal sources said his striking down of the sub-sections — S99.9 and Section 99.10 — will affect the operation of the criminal justice system on a daily basis and is likely to lead to immediate challenges by affected persons.

Legislation will have to be urgently enacted to remedy the situation, several sources stressed.

The judge has adjourned making final orders in the six cases involved for two weeks to allow lawyers for the men, the Director of Public Prosections (DPP) and the State consider his findings.

His judgment was delivered in separate cases brought by six young men against the DPP and State, all of which argued the provisions of Section 99 concerning activation of suspended sentences were unfair and breached their constitutional rights to equal treatment before the law.

The six were convicted of offences ranging from public order offences to driving without insurance, attempted robbery and violent disorder.

Section 99, previously twice amended, governs the power to suspend sentences and activate sentences already suspended.

It has been frequently criticised by judges and Supreme Court judge Mr Justice Donal O’Donnell previously said it has given rise to “innumerable practical difficulties and problems of interpretation”.

Mr Justice Moriarty said he agreed with Mr Justice O’Donnell Section 99 was in need of “urgent and comprehensive review”.

Section 99 was drafted and enacted by persons “quite unacquainted of the actual practices of the courts”, particularly of the District and Circuit Courts, he said. The “myriad” difficulties could have been avoided if any proper effort to consult the judges who actually implement the procedures for activation of a suspended sentence.

Section 99 has already been amended twice but it was “beyond doubt” the intended path has proved “thorny, beset with problems and results in recurring applications on behalf of such accused persons”, whether via applications under Article 40 of the Constitution or other avenues, he said.

Outlining some of the difficulties, he said one of the six cases involved a man convicted of a minor District Court offence who was about to be sentenced by that court when it became apparent a prior suspended sentence imposed by Dublin Circuit Criminal Court (DCCC) remained operative.

The District Court, as required by Section 99, sent the matter to the original suspending court, DCCC, to decide whether the original suspension should be activated.

In what is a constant argument in similar cases, the accused said he wanted to appeal the District Court conviction and have that appeal decided before the suspension issue went to DCCC, the judge said.

That option appeared to be precluded by the amended wording of Section 99 and it also appeared, if the DCCC did activate the suspended sentence, the man would spend time in prison before his appeal. If he ultimately won that appeal, the basis for activation would have been incorrect and his time in prison unjustified.

On those and other grounds, all six argued the procedure for activating suspended sentences was an unfair and unwarranted interference with their rights, including to appeal District Court orders, to liberty and to equality of treatment before the law.

Mr Justice Moriarty said he was persuaded, on foot of the facts of the six cases and the arguments made by the plaintiffs, that the disputed provisions of Section 99 were unconstitutional.