Ms. Glawischnig-Piesczek did not respond to requests for comment.
The decision highlights a widening gap between the United States and Europe on regulating the technology industry. Europe has imposed tougher policies on privacy, antitrust, copyright and content moderation, while the United States has traditionally had a more hands-off approach.
Yet as Europe has enacted tougher policies, courts are being asked to clarify their reach, including if Facebook, Google and other platforms must apply the rules beyond the borders of the 28-nation European Union.
Last week, the European Court of Justice limited the reach of the privacy law known as the “right to be forgotten,” which allows European citizens to demand Google remove links to sensitive personal data from search results. The court said Google could not be ordered to remove links to websites globally, except in certain circumstances when weighed against the rights to free expression and the public’s right to information
On Thursday, the Luxembourg-based court turned its attention to the reach of European defamation laws. It ruled that a national court of a European Union country could order Facebook to remove posts considered defamatory in regions beyond its jurisdiction.
The decision should not be expected to lead to a flood of orders against Facebook to take down content globally, said David Erdos, deputy director of the Center for Intellectual Property and Information Law at Cambridge University. The opinion was narrowly crafted, he said, and urged national courts to weigh any bans carefully against international laws.
“Courts will be feeling their way for years to come,” he said.
The difference between today’s decision and last week’s ruling limiting the reach of the right to be forgotten is that an Austrian court had specifically found, within its decision, that the offensive comments toward Ms. Glawischnig-Piesczek were illegal.
The court on Thursday said that while Facebook wasn’t liable for the disparaging comments posted about Ms. Glawischnig-Piesczek, it had an obligation to take down the posts after a court ruled them defamatory. Facebook, the court said, “did not act expeditiously to remove or to disable access to that information.”