A teacher is suing Facebook over postings alleging a failure to safeguard pupils at a west Belfast secondary school, the High Court has heard.
Libel action is also being taken against an anonymous group of parents behind a social media page focused on De La Salle College.
Proceedings centre on claims that a priest invited into the Catholic boys' school questioned three students about their sex lives during confession.
Allegations that a group of pupils were then taken to see the same priest in the Republic after he was banned from the school also feature in the case.
The teacher who has brought the case is not being named for legal reasons.
Damages are being sought against Facebook and a second defendant referred to as a person or persons unknown adopting the pseudonym Concerned Parents of De La Salle.
Earlier this year an independent review commissioned by the school's board of governors examined its child protection measures.
The report looked into allegations by three pupils that the priest made inappropriate comments to them during a visit in May 2013.
It involved claims of being asked about masturbating and viewing pornography.
The complaints were referred to the PSNI, but no further police action was taken as none of the boys' parents wanted to make a complaint, according to the published review.
It found that, in all cases, the pupils' allegations had been reported to the relevant designated teacher.
The teacher taking the legal action was never subject to any police investigation.
A preliminary hearing in the case involved arguments on the meanings behind comments posted on the Concerned Parents of De La Salle Facebook page.
Lawyers for the teacher and the social media giant advanced different assessments on the level and seriousness of the alleged defamatory content.
No defence has been entered at this stage on behalf of the second, unidentified defendant.
Gavin Millar QC, for the plaintiff, contended that the allegations directed at his client were portrayed as facts.
"The core of the libel is the criticism for a failure to safeguard children in (the teacher's) care," he said.
But counsel for Facebook told the judge that the comments could have a range of meanings.
Following submissions Mr Justice Burgess reserved judgment on the initial stage in the case.
