The ruling came in a case over Hungarian news outlet Index.hu being sued for messages on its forum, the report says.
Readers posted angry comments about a real-estate company, which sued the portal and an association for Hungarian internet firms in local courts for allowing the comments to be published.
Index.hu said it had immediately removed the offending comments after they had been flagged, but that it could not be held liable for everything readers posted, reads The Guardian report.
It said the news site’s lawyers argued that liability for reader comments “would have serious adverse repercussions for the freedom of expression and the democratic openness in the age of the internet”.
The ECHR said agreed and said that Hungarian courts had failed to balance the need to prevent abuse with the right to free expression, says The Guardian.
Hungary is regularly criticised by rights groups for its treatment of the media, with Prime Minister Viktor Orban, accused of muzzling the press, it said in the report.