The Irish High Court has slapped down Facebook's bid to further delay the battle over the legality of its transatlantic data transfers in a critical judgment that questions the firm's previous conduct in court.

On Monday, Facebook applied for a stay in the long-running case over the way in which it transfers data from the EU to the US, which was initially brought by privacy activist Max Schrems back in 2013.

The case is now considering whether the standard contractural clauses Facebook uses to transfer data to the US provide sufficient protections for EU data subjects. As part of this the Irish High Court has referred a detailed set of questions up to the Court of Justice of the European Union.

Facebook wants to appeal against the decision, and asked the court to stay the referral until the Irish Supreme Court has decided if it will hear that appeal.

But the firm's Monday submissions got short shrift from Justice Costello, who issued a 12-page judgment (PDF) that not only denied the social network its request but also criticised its conduct in previous proceedings.

Her criticisms centre around the fact Facebook said the first grounds of its appeal to the Supreme Court would be that the EU directive in question will be replaced by the General Data Protection Regulation, and so the referral would be rendered moot by the time it reached the CJEU (it can take months if not years for the court to hear such cases).

However, the judge said Facebook had ample time to bring up its concerns about there being a "clock ticking down" in the case. It even, along with the other parties, requested that the hearing dates be postponed.

Moreover, Costello pointed out that on day 15 of a three-week hearing in March 2017, she had asked about the GDPR and whether it would render the case moot.

In today's judgment, she printed the short exchange in full, noting it was the sole discussion "in a case where innumerable points were argued intensely over 21 days".

If Facebook had wanted to argue that the reference to the CJEU would be rendered moot in such a way, she said, that argument "ought to have been made explicitly and clearly and not in the oblique passing fashion, one might almost say as an aside" as they were represented during the hearing.

"The fact that the point is only now being raised gives rise to considerable concern as to the conduct of the case by Facebook and the manner in which it has dealt with the court," Costello said.

She emphasised that because Facebook had not made this clear, the court had not expedited the case in a bid to ensure it wasn't decided by "effluxion of time".

"Clearly the existing delays have already potentially gravely prejudiced the DPC [Irish Data Protection Commissioner] and Mr Schrems. I do not propose to exacerbate this potential prejudice any further," she stated.

Elsewhere in the judgment, Costello noted that the data protection commissioner, Helen Dixon, had argued that if the standard contractural clauses under debate do not comply with EU laws "then the data of millions of data subjects may continue to be processed unlawfully".

"In my opinion very real prejudice is potentially suffered by Mr Schrems and the millions of EU data subjects if the matter is further delayed by a stay as sought in this case. Their potential loss is unquantifiable and incapable of being remedied."

The Register has asked Facebook to comment. ®