Facebook's sharing of data on its European users with the U.S. is legal and provides sufficient protections, the legal advisor to the EU's top court said Thursday.

In a symbolic win for the social network, Henrik Saugmandsgaard Oe, advocate general to the Court of Justice of the European Union (CJEU), said the use of so-called standard contractual clauses by Facebook and other firms to transfer information abroad is "valid."

"Standard contractual clauses for the transfer of personal data to processors established in third countries is valid," he said in written opinion Thursday.

His non-binding opinion is not a ruling as such, but legal experts say opinions from the advocate general are typically followed by the court in a majority of cases. The CJEU will rule on the case in the coming months.

Privacy activist Max Schrems has been battling Facebook and other internet platforms in the courts for several years. His main contention is with the exporting of data from Europe for processing in the U.S., claiming it aids Washington's surveillance of citizens and governments in the bloc.

He successfully brought down the EU's "Safe Habor" data regime in 2015, but argues the bloc's new "Privacy Shield" arrangement on EU-U.S. data transfers is merely an update to the previous system and remains unlawful.

The CJEU advocate general in his written opinion appeared to sympathize with Schrems' concerns about the Privacy Shield, "in the light of the right to respect for private life and the right to an effective remedy."

He said that there was ultimately an "obligation" on data controllers and regulatory authorities to suspend the transfer of data where it conflicts with the laws of the country that information is being sent to.