Ruling on murderer Graham Dwyer's mobile data retention challenge to be given next month

Sources in Luxembourg confirmed to the Sunday World at the weekend that the court would announce the date when the ruling on the case will be published “within a couple of weeks”

The ECJ press office said on Monday that the judgment would be given on April 5.

Mobile phone data location evidence was key to identifying the Foxrock architect as a suspect in the disappearance of care worker Elaine O’Hara in 2012.

But the killer has since taken a successful High Court challenge to the Communications (Retention of Data) Act 2011, the law under which his data was retained and seized.

The case has caused concern across Europe after the Supreme Court referred ­questions to the CJEU.

“I don’t think the public is really alive to what the consequences of this are,” a senior legal figure told Sunday World last November. “A lot of crimes simply won’t get solved in future.”

Advocate General Manuel Campos Sánchez-Bordona said the indiscriminate retention of mobile phone data could be justified only in cases involving national security and could not be justified for the prosecuting offences, even serious ones such as murder.

In doing so he rejected appeals by several countries at a hearing in September, who maintained the retention of mobile phone data was essential for law enforcement.

His opinion is being seen as a victory for privacy advocates and a crushing defeat for law enforcement. The opinion is non-binding but is expected to be adopted by the CJEU when it rules on the Dwyer questions.

Courts in Germany and France also submitted questions relating to the scope of what is permissible under EU data retention law.

The law struck down by the High Court required mobile operators to keep data for two years and allowed gardaí access it on the request of a chief superintendent. The Advocate General’s opinion will have reinforced the ruling.

He also cited previous CJEU case law indicating bulk retention of data was only permitted for the purposes of safeguarding national security where an EU member state is confronted with a serious threat that is shown to be genuine and present or foreseeable.

Even then, a court must have oversight and the time period covered must be no longer than is “strictly necessary”.

Another issue that will concern Irish authorities is that the Supreme Court, which has already indicated it will find the 2011 act invalid, has been told it cannot limit the retrospective effect of that declaration.

This should pave the way for Dwyer’s lawyers to argue in the Court of Appeal that evidence gleaned from the retained data should not have been entered in evidence.

It may also open the door to challenges to other convictions, although these may have a chance of success only if the issue was raised at trial.

Then there are concerns about investigations going forward because the use of retained data was considered a valuable tool for detectives. The issue cropped up during the trial of four men for the kidnap and torture of Mannok (formerly QIH) executive Kevin Lunney.

The Special Criminal Court opted not to rely on call data and location records in convicting three of the four accused, saying there was other evidence to rely on.

The 2011 act was brought in as the result of a 2006 EU directive, which was a response to 9/11 and other terrorist attacks. That directive was later struck down by the CJEU in 2014 following a case led by privacy campaign group Digital Rights Ireland.