Facebook is trying to keep the European Court of Justice (ECJ) from reviewing an Irish privacy case, fearing potential limitations on its ability to move customer data from the EU to the US.

Facebook’s headquarters for most of its non-US markets is in Dublin. The Irish High Court ruled that US surveillance programs permit the “mass indiscriminate” processing of the private data of European citizens and noted the lack of effective legal remedies against that kind of surveillance, given that the US government does not typically notify people who are being subjected to spying.

The Irish court has ordered the referral of the case to the ECJ in order to determine whether methods used for data transfers are legal. If the ECJ agrees with the decision of the Irish court, that could mean trouble ahead for thousands of tech firms, which transfer huge amounts of data from the EU to the US every day.

Irish #HighCourt reserves judgement on stay for #SCC / #PrivacyShield reference to @EUCourtPress - judgement expected within a week. DPC and we argued against a stay. Facebook wants to stop the reference. #IfYouCantWinDelayhttps://t.co/U4ITKEBAEg — Max Schrems (@maxschrems) April 30, 2018

The case against Facebook was filed by Austrian lawyer and privacy activist Max Schrems, who questions whether big technology companies like Facebook give Europeans adequate protection from US surveillance systems.

Facebook lawyer Paul Gallagher told the court that the social media giant was seeking a stay on the ruling, in order to give the Irish Supreme Court time to decide if it would hear an appeal of the High Court’s decision.

Schrems originally brought his case against Facebook after NSA whistleblower Edward Snowden revealed massive privacy violations through NSA spying programs. In 2015, the ECJ invalidated the Safe Harbor agreement — the legal agreement by which Facebook could transfer data from European citizens to the US.

Read more

Following that ruling, the US and EU came up with a new agreement called Privacy Shield, which was designed to withstand inspection from the ECJ — but Schrems’ new complaint questions the reliability of this arrangement to protect user data from US mass surveillance systems.

Facebook argued in court that data belonging to European users is adequately protected and that there are sufficient remedies available if users are illegally surveilled.

The case is the latest privacy-related headache for Facebook, which is already dealing with fallout from the Cambridge Analytica scandal. The British tech firm illegally harvested the data of 87 million Facebook users and allegedly used it for political messaging during the 2016 US presidential election.