Explainer: What is the basis for killer Dwyer's High Court challenge and how conceivable is it he could be freed?
Convicted killer Graham Dwyer has brought a challenge to the legislation gardaí used to obtain his mobile phone data, evidence which proved crucial in his conviction for the murder of Elaine O'Hara.
Why has he brought the case?
Dwyer still maintains he is innocent of the murder of childcare worker O'Hara, whom he met via a website for people with interests in bondage, domination, submission and masochism.
She disappeared in August 2012 and her remains were not found until 13 months later in a forest at Killakee in the Dublin Mountains.
Dwyer was jailed for life in March 2015 following a trial which heard disturbing evidence of how he engaged in acts of stabbing for his sexual gratification.
The former architect has brought this case to the High Court in the hope a ruling in his favour will bolster his chances of succeeding in a separate challenge to his conviction at the Court of Appeal.
What was so important about mobile phone evidence in the murder case?
It is doubtful Elaine O'Hara's murder would have been solved had it not been for mobile phone data obtained by gardaí. As Dwyer's counsel Remy Farrell SC told the High Court yesterday, the suspicions which led gardaí to arrest his client were based significantly on this material.
What sort of data are gardaí allowed to obtain?
Under the Communications (Retention of Data) Act 2011, a garda of the rank of chief superintendent can request that a telecommunications provider disclose data relating to a particular mobile phone number for the purposes of investigating, preventing or prosecuting a serious crime. This data can include call and text traffic and the location of the phone when calls or texts were made or when it pinged off a nearby mast. Providers must retain such information for up to two years.
Using this law, gardaí obtained data associated with Dwyer's work mobile phone and other handsets discovered during the course of their investigation.
What did they find?
Using cell-site analysis, detectives were able to pinpoint roughly where Dwyer was at certain points in time based on the movements of his phone.
This assisted investigators to establish his routine in the months prior to Ms O'Hara's disappearance.
Crucially, cell-site analysis was also able to link the movements of Dwyer's work phone to those of a Nokia mobile phone discovered in the Vartry Reservoir in Co Wicklow in September 2013.
When Dwyer went somewhere, he tended to bring both phones with him.
This second handset, known as the "master" phone, was used by Dwyer to communicate with Ms O'Hara. She used another Nokia handset, known as the "slave" phone, which gardaí recovered during the investigation. Both the "master" and "slave" phones were detected in Shankill, Co Dublin, on the night Ms O'Hara disappeared.
Detectives were also able to "resurrect" text messages from the phones, as well as messages that were backed up on a computer.
This enabled them to reconstruct conversations between Dwyer and his victim.
What is the basis for Dwyer's challenge to the legislation?
Dwyer's legal team argues the 2011 Act used by gardaí to obtain his phone data gave effect to the EU's 2006 Data Retention Directive, under which members could require telecommunications providers to retain data for up to two years.
But in April 2014, the Grand Chamber of the European Court of Justice ruled that the directive was invalid. Among the flaws the court identified was that the directive interfered more than was strictly necessary with fundamental rights to respect for private life and the protection of personal data. It also found the directive did not provide sufficient safeguards against the risk of abuse or unlawful access of data.
How did Irish authorities react to the ruling?
While other EU countries have taken steps to amend their national laws, Ireland has not done so.
In response to the case brought by Dwyer, the State denies the 2011 Act was promulgated pursuant to the directive. It also denies that the European Court of Justice ruling applies to the 2011 Act.
What happens if Dwyer's case is successful?
He wants the court to rule that the 2011 Act is incompatible with the EU Charter of Fundamental Rights and the European Convention on Human Rights, as well as being repugnant to a number of articles of the Irish Constitution. If he were to win, it would assist his murder appeal as it would raise question marks over the manner in which crucial evidence was obtained.
How conceivable is it he could be freed?
Even if Dwyer were to win his current case, the odds would still be very much stacked against him succeeding in a murder appeal.
There is no guarantee the Court of Appeal would throw out the mobile phone evidence against him.
A trump card for the DPP may be a 2015 Supreme Court ruling which means that evidence obtained in breach of an accused's constitutional rights does not necessarily have to be excluded at trial if the breach involved was not conscious and deliberate.