The EU's top court, the European Court of Justice, ruled that states can order Facebook to remove illegal content online.
"EU law does not preclude a host provider such as Facebook from being ordered to remove identical and, in certain circumstances, equivalent comments previously declared to be illegal," the court said in its ruling.
"EU law does not preclude such an injunction from producing effects worldwide, within the framework of the relevant international law which it is for Member States to take into account," it added in the press release.
The ruling was sparked by the case of Eva Glawischnig-Piesczek, the former chair of Austria's parliamentary group die Grünen” (the Greens), who brought Facebook Ireland to court over an anonymous post that called her a "lousy traitor", according to Columbia University's Global Freedom of Expression analysis of the case.
The Austrian Supreme Court had determined that the Facebook post was meant to insult and defame Glawischnig-Piesczek.
A Facebook company spokesperson told Euronews that the judgement raised "critical questions" about "freedom of expression and the role that internet companies should play in monitoring, interpreting and removing speech that might be illegal in any particular country."
"It undermines the long-standing principle that one country does not have the right to impose its laws on speech on another country... We hope the courts take a proportionate and measured approach, to avoid having a chilling effect on freedom of expression," the spokesperson said.
This story is currently being updated.