Mobile phone data used in Graham Dwyer case in breach of EU law, court rules

Judgment has potentially significant adverse implications for fight against serious crime

Convicted murderer Graham Dwyer has won a significant victory at Europe's top court in his challenge concerning the mobile phone metadata evidence used to convict him.

The European Court of Justice (CJEU) upheld Dwyer’s challenge to the legality of Ireland’s metadata regime as set out in some provisions of a 2011 law. Phone metadata played a key role in the securing Dwyer’s conviction in 2015 for the murder of childcare worker Elaine O’Hara in 2012.

In a judgment on Tuesday with potentially significant adverse implications for the fight against serious crime in Ireland and across Europe, the CJEU said European law precludes national legislation allowing for the general and indiscriminate retention of phone metadata for the prevention of serious crime.

Maintaining the 2011 law would mean continuing to impose obligations on electronic telecommunications services providers which are contrary to European Union law and which “seriously interfere with the fundamental rights of the persons whose data have been retained”, the court said.


Its judgment clarifies what is permissible under EU law in relation to retention of, and access to, phone metadata.

EU law, it said, does not preclude, for the purpose of combating serious crime and preventing threats to public security, national laws for targeted retention of phone traffic and location data limited to categories of persons concerned or a geographical criterion, such as the average crime rate in a particular area or strategic places such as airports.

It also does not prevent the enactment of national laws permitting general and indiscriminate retention of internet addresses assigned to the source of an internet connection, general and indiscriminate retention of data relating to the civil identity of users of electronic communication systems and the ‘quick freeze’ of traffic and location data held by service providers, it said.

National laws requiring registration of the identity of purchasers of prepaid sim cards are permissible.


EU law, the court said, does not preclude member states enacting measures for expedited data retention at the first stage of an investigation into a serious public security treat or a possible serious crime and for such measures to be extended to traffic and location data relating to suspects of such crimes.

Any system for targeted data retention must be subject to effective safeguards against the risk of abuse for the affected data subjects and to independent oversight, the court stressed.

It also made clear that the Irish courts cannot impose a time limit on a declaration that the 2011 law is invalid.

The Supreme Court, before finally deciding the State’s appeal against a 2018 High Court decision in favour of Dwyer’s challenge to the 2011 law, had asked the CJEU to rule whether the phone metadata retention regime here breaches EU law. It has answered in the affirmative.

The case must now go back to the Supreme Court, which will deliver its final judgment later on the State’s appeal.

There is no certainty the CJEU findings will lead to success for Dwyer in his separate appeal to the Court of Appeal against his conviction.

Rights conferred

The CJEU made clear in its judgment that the admissibility of evidence obtained under the data-retention law is a matter for national law, subject to “the principles of equivalence and effectiveness”. That means, among other things, that rights conferred by EU law should not be rendered impossible.

An important Supreme Court decision, DPP v JC, allowing otherwise inadmissible evidence to be admitted if it was obtained on foot of an inadvertent breach of a constitutional right is likely to be wielded by the Director of Public Prosecutions in opposing Dwyer’s appeal, a date for which has yet to be set.

Minister for Justice Helen McEntee said in a statement that her department and the office of the Attorney General would consider the Supreme Court’s judgment in the Dwyer data case when it is finalised.

She said she expected the judgment would bring clarity to the area and inform legislation to support the work of An Garda Síochána in tackling crime and carrying out investigations.

Mary Carolan

Mary Carolan

Mary Carolan is the Legal Affairs Correspondent of the Irish Times