The EU member's constitutional court rejected a complaint by the Association of Hungarian Content Providers (MTE) -- whose members include popular online news sites -- against an earlier supreme court ruling.
The supreme court had said some "below-the-line" comments about a real estate company advertising on an MTE webpage were "humiliating" and "crossed the boundaries of free speech".
Yesterday, the constitutional court upheld the ruling that operators should be responsible for comments on their websites, even if they are moderated or removed immediately on request.
The Hungarian Civil Liberties Union (TASZ) however said the ruling meant "unconditional responsibility" for website operators.
That will make it risky to allow any commentary at all on websites, TASZ said, adding that it would restrict political debate, and have a "chilling effect" on freedom of speech.