Glawischnig-Piesczek has not responded to requests for comment.
The decision highlights a growing gap between the United States and Europe in regulating the technology sector. Europe has imposed stricter policies on privacy, antitrust, copyright and content moderation, while the United States has traditionally taken a more practical approach.
However, as Europe has adopted stricter policies, courts are being asked to clarify their scope, including whether Facebook, Google and other platforms should enforce rules across the European Union's 28-country borders.
Last week, the European Court of Justice limited the scope of the “right to be forgotten” privacy law, which allows European citizens to require Google to remove links to sensitive personal data from search results. The court said Google could not be ordered to remove links to websites worldwide except in certain circumstances when compared to free speech rights and the public's right to information.
On Thursday, the Luxembourg court turned its attention to the scope of European defamation laws. It ruled that a national court of a European Union country could order Facebook to remove postings considered defamatory in regions outside its jurisdiction.
The decision should not lead to a flood of requests against Facebook to topple content globally, said David Erdos, deputy director of the Center for Intellectual Property and Information Law at Cambridge University. The opinion was strictly elaborated, he said, and urged national courts to carefully consider any prohibition against international law.
"The courts will feel good in the coming years," he said.
The difference between today's decision and last week's decision limiting the scope of the right to be forgotten is that an Austrian court had specifically found, in its ruling, that the offensive comments against Glawischnig-Piesczek were illegal.
The court said on Thursday that while Facebook is not responsible for the derogatory comments posted about Glawischnig-Piesczek, it has an obligation to remove the posts after the court finds them defamatory. Facebook, the court said, "did not act quickly to remove or disable access to this information."