A European court has been asked to rule on a landmark case which seeks to force watchdogs to audit the personal data Facebook releases to US spy chiefs.
The High Court in Dublin has referred to Luxembourg a challenge by an Austrian privacy campaigner on the back of the Prism surveillance op exposed by whistleblower Edward Snowden.
Max Schrems's initial attempt to have the social media giant audited over data that its Irish arm allegedly passes on to the US National Security Agency (NSA) was dismissed last year by Ireland's Data Protection Commission.
Today, Judge Desmond Hogan ordered the privacy challenge - taken in the Irish courts by Mr Schrems's Europe V Facebook campaign - be referred to the European Court of Justice.
The judge said evidence suggests that personal data is routinely accessed on a "mass and undifferentiated basis" by the US security authorities.
He said Facebook users should have their privacy respected under the Irish Constitution.
"For such interception of communications to be constitutionally valid, it would, accordingly, be necessary to demonstrate that this interception and surveillance of individuals or groups of individuals was objectively justified in the interests of the suppression of crime and national security and, further, that any such interception was attended by the appropriate and verifiable safeguards," the judge said.
Judge Hogan adjourned the case in the Irish courts while European judges look at two questions.
He is asking Luxembourg to examine whether Ireland's data watchdog is bound by what is known as Safe Harbour - a European Commission decision from 2000 that US data protection rules are adequate if information is passed by companies to its security agencies on a "self-certify" basis.
Judge Hogan is also asking whether an investigation can be launched in Ireland in light of the Snowden revelations that internet data and communications were being intercepted by the NSA on a global scale.
Examining the background to Mr Schrems's challenge, Judge Hogan said only the naive or credulous could have been surprised by the Snowden expose.
"Only the foolish would deny that the US has, by virtue of its superpower status, either assumed - or, if you prefer, has had cast upon it - far-reaching global security responsibilities," he said.
"It is probably the only world power with a global reach which can effectively monitor the activities of rogue states, advanced terrorist groups and major organised crime, even if the support of allied states such as the UK is also of great assistance.
"The monitoring of global communications - subject, of course, to key safeguards - is accordingly regarded essential if the US is to discharge the mandate which it has assumed.
"These surveillance programmes have undoubtedly saved many lives and have helped to ensure a high level of security, both throughout the western world and elsewhere.
"But there may also be suspicion in some quarters that this type of surveillance has had collateral objects and effects, including the preservation and reinforcing of American global political and economic power."
The case will be mentioned in the High Court in two weeks before the issue is sent to the European court.
Mr Schrems is understood to be in Vienna examining the ruling.
Mr Schrems said he would take more time to study the referral.
He said: "We did not have time to study the judgment in all detail, but having the matter referred to the ECJ is the best thing that could have happened.
"We expected to win it in Ireland, but having a European ruling on it is more than we could have asked for."
Billy Hawkes, the Data Protection Commissioner in Ireland, said the ruling backs his position that the issues raised by Mr Schrems are undoubtedly serious and focus on wider issues of European law.
"The commissioner acknowledges and accepts the court's view that, because the data privacy issues raised by the Snowden revelations are so serious, it is appropriate that the European Court of Justice should be asked to consider the critical issue," his office said in a statement.
"The commissioner looks forward to participating in that process in due course."