Facebook on Monday temporarily fought off a collective lawsuit valued at up to 3 billion pounds ($3.7 billion) over allegations the social media giant abused its dominant position to monetize users' personal data.
However, a London tribunal gave the proposed claimants' lawyers up to six months to "have another go" at establishing any alleged losses by users.
Meta Platforms, the parent company of the Facebook group, faces a mass action brought on behalf of around 45 million Facebook users in Britain.
Legal academic Liza Lovdahl Gormsen, who is bringing the case, says Facebook users were not properly compensated for the value of personal data they had to provide to use the platform.
Her lawyers last month asked the Competition Appeal Tribunal to certify the case under the UK's collective proceedings regime – which is roughly equivalent to the class action regime in the United States.
But the Tribunal ruled on Monday that Lovdahl Gormsen's methodology of establishing any losses suffered by Facebook users needed "root-and-branch re-evaluation" for the case to continue.
Judge Marcus Smith did, however, give Lovdahl Gormsen's lawyers six months to "file additional evidence setting out a new and better blueprint leading to an effective trial".
A spokesperson for Meta said the company welcomed the decision and referred to its previous statement that the lawsuit is "entirely without merit".
Lawyers representing Lovdahl Gormsen did not immediately respond to a request for comment.