An Irishman described by the FBI as the world's "largest facilitator of child porn" has lost his legal challenges to his extradition to the United States and to the decision not to prosecute him in Ireland.

Eric Eoin Marques is alleged to be the owner and administrator of an anonymous hosting site known as Freedom Hosting. 

He is wanted by the US authorities to face charges relating to conspiring to distribute and advertise child abuse images and advertising and distributing child abuse images.

The charges against Mr Marques relate to images on over 100 "anonymous websites" described as being extremely violent, graphic and depicting the rape and torture of pre-pubescent children.

The 30-year-old with an address at Mountjoy Square in central Dublin has been in custody since his arrest in August 2013.

His surrender was ordered by the High Court last December but this was stayed pending an appeal.

Mr Justice Michael Peart said he agreed with the High Court's conclusion that the Director of Public Prosecutions' decision not to prosecute Mr Marques in Ireland was "not reviewable" and the director was "not obliged to give reasons" for her decision not to prosecute.

Mr Marques had no right be it statutory, constitutional or otherwise to be prosecuted for an offence in Ireland even where he offers to plead guilty.

There was "simply no such right known to the law," Mr Justice Peart said.

Citing case law, he said the constitutional right of access to the courts is a right to initiate litigation, not a right to compel suit or prosecution.

Mr Justice Peart said Mr Marques had no free standing right to be given reasons for the decision not to prosecute.

If he had no right to even request what he was requesting, he had no right to reasons why his request was refused.

Mr Justice George Birmingham and Mr Justice Garrett Sheehan said they agreed with Mr Justice Peart's judgment.

In relation to Mr Marques' appeal against his extradition order, Mr Justice Peart said the single ground of appeal was essentially that, if he was convicted, Mr Marques would be exposed to a sentencing regime in America that would be unconstitutional here.

It was submitted that a sentencing judge in America is "obliged" to take account of other uncharged conduct as well as conduct an accused has been acquitted of at sentencing and to do so on the lower standard of proof - on the balance of probabilities.

Mr Justice Peart said the apprehensions expressed by Mr Marques were based on speculation.

In so far as he feared that a potential sentence could be enhanced by reference to him allegedly making a financial gain, that fear could not amount to a substantial or real risk of unfairness.

Mr Justice Peart said he agreed with the High Court judge's conclusions that all of the common law cases referred to the court concerned the burden of proof at trial.

None of them demonstrated a "universal requirement that all matters at sentencing" be determined beyond reasonable doubt.

Referring to the European Court of Human Rights case known as 'Abu Qatada v the United Kingdon', Mr Justice Peart said the facts relied on by Mr Marques "cannot by any stretch of the imagination be compared to the heinous and egregious prospect of a conviction based upon evidence or confessions … extracted through the use of torture".

That, "unlike the apprehended regime in the present case", was something that very clearly breached an international norm.

Mr Justice Birmingham and Mr Justice Sheehan again said they agreed with Mr Justice Peart's judgment.

The case will come before the Court of Appeal next week to determine final orders.