Facebook is dealing with a new European headache over its WhatsApp acquisition after the Hamburg Commissioner for Data Protection today announced a decision prohibiting the two services from sharing data from their respective users.

Following the acquisition of WhatsApp in 2014, Facebook had initially said that user data would not be merged or shared between the two services. However, in August 2016 the companies released new Terms of Service stating that WhatsApp user data would be transferred to Facebook, a process that did not appear to ask for user permission or create an opt-out mechanism, according to the commission.

The commission did note that it would still be possible to create a process for WhatsApp users to opt into sharing their data. Specifically, it was initiating a mass transfer without seeking permission that the commission declared illegal.

That practice has also prompted an investigation by the European Union, which had previously approved the merger under the belief that the data would not be shared. Last December, the EU declared that Facebook may have made misleading statements during the merger review and could be subject to financial penalties of up to $180 million.

Facebook’s response to the E.U. inquiry is now under review.

Today’s Hamburg ruling will further complicate the issue for Facebook. When it comes to data and privacy, rules in the EU are still somewhat fractured across the 28 member states. The Hamburg commission governs German users, and the ruling made it quite clear the commission believes there is no legal rationale for allowing Facebook to share the information.

“Facebook can not invoke interests of its own business because the complete data exchange is neither necessary for the purpose of network security or business analysis nor for advertising optimization,” the commission wrote. “Furthermore, the court clarifies that there is no effective consent from WhatsApp users for a data exchange with Facebook.”

The commission noted that the decision covers the 35 million WhatsApp users in Germany, but said it also hopes the decision will set a precedent for other data commissioners across the continent.