Facebook remains liable in damages for details about a convicted child abuser featuring on pages set up to name and shame paedophiles in Northern Ireland, the Court of Appeal has ruled.
But senior judges restricted the period when the social network knew private information was being published - meaning a £20,000 compensation award to the sex offender could now be cut.
Lord Chief Justice Sir Declan Morgan indicated yesterday that a further hearing will explore the appropriate level of payout due to the changed circumstances.
Facebook was sued along with so-called paedophile hunter Joe McCloskey over an online forum operated by the Limavady man.
The sex offender, identified only as CG, issued proceedings after his photograph and details appeared on the page 'Keeping Our Kids Safe From Predators 2'.
In a landmark ruling last year the High Court held both the social media giant and Mr McCloskey liable for misusing private information.
CG was released from jail in 2012 after serving a sentence for gross indecency and indecent assault offences against a young girl and a teenage boy.
Now aged in his 40s, he remains under supervision by the authorities and has been assessed as posing no significant risk to the public.
His lawyers argued that an online campaign after his details appeared on the page had reached the level of dangerous vigilantism.
Amid a string of abusive comments and information on his location, one user called for him to be hanged. Others endorsed shooting or castrating him.
Ruling in favour of CG's right to privacy, the High Court awarded damages in the total sum of £20,000, with Mr McCloskey liable for £15,000 of that amount.
Since the verdict two of CG's victims have issued writs against him.
An injunction was also secured to stop any payout to the sex offender until those cases are dealt with.
Mr McCloskey, who was also held liable for harassment, abandoned his attempt to overturn the findings against him.
Central to Facebook's appeal was the status of notification letters issued by CG's lawyers in a bid to have the postings removed.
Contending there had been a failure to properly identify the unlawful material, counsel insisted the sex offender had to live with name-calling as part of his conviction. Delivering judgment yesterday, Sir Declan stressed the fundamental importance of the principle of open justice - particularly where the public is concerned about the punishment, rehabilitation and risk posed by an offender.
A central issue was whether Facebook had knowledge about the publication of private information.
"The proper operation of the notice and take down procedure should have caused Facebook to respond," Sir Declan said.
He held that the onus was on the company to remove the information expeditiously - a step not taken until early the next month.
The judge confirmed: "We find that Facebook are liable to the respondent in damages for misuse of private information for the period from November 26, 2013 until December 4/5, 2013. Facebook's appeal in relation to the remaining periods is allowed."
With the case due to be relisted for further submissions on compensation and costs, Sir Declan said it would deal with "what is the appropriate quantum of damages now, in light of the changed circumstances".