The European Court of Human Rights (ECHR) has issued a decision that anti-censorship campaigners say could spell an end to anonymous website comments in the EU.

The judgment came through on Thursday in the case of Delfi AS v. Estonia. Delfi is an Estonian news site that had been found liable by a court in that country for offensive comments posted by anonymous users under one of its stories—it went to the ECHR claiming this violated its right to freedom of expression, but the human rights court disagreed.

This all traces back to the start of 2006, when Delfi carried a story about a ferry company that had changed its routes in a way that delayed the opening of new ice roads to various islands. Enraged readers wrote nasty things about the ferry firm, which successfully sued Delfi, winning around €320 ($434) in damages.

Having established that the comments were defamatory and Delfi should have expected that, given the nature of the article, the ECHR’s ruling (which can still be appealed) noted that the comments had not been taken down by Delfi’s automated system for catching naughty words, nor by its notice-and-take-down system.

Now here comes the crucial bit for online publishers. Although Delfi’s site was clear that commenters were themselves liable for what they wrote, which would theoretically have allowed the ferry company to sue them rather than Delfi, the commenters were anonymous.

And so, according to the ECHR’s subsequent statement:

“Making Delfi legally responsible for the comments was therefore practical; but it was also reasonable, because the news portal received commercial benefit from comments being made.”

Index on Censorship’s Padraig Reidy responded by saying : “It is difficult to see how any site would allow anonymous comments if this ruling stands as precedent.”

What it could stand as a precedent for is not entirely clear. The Delfi case was quite specific: it was largely about the legality of Estonia’s interpretation of EU free-expression law (which the court upheld); the comments were apparently merely offensive rather than whistleblowing or anything like that; the fine in question was small and found to be reasonable; and Delfi’s systems for picking up abusive comments seem to have failed in this instance. Also, the EU is not America—it has fairly good guarantees for free expression, but not as cast-iron as those stateside.

But nonetheless, particularly in the context of a wider questioning of anonymous comments, it’s not hard to see why Index on Censorship finds the ruling troubling. There can be great value in anonymous comments, and a ruling such as this may have a chilling effect if it leads publishers and site operators to decide the potential liability is too great.