The Advocate General in Europe’s highest court has said that the privacy campaigner Max Schrems is entitled to use his consumer status to sue Facebook Ireland through the Austrian courts.

However, Mr Schrems' consumer privilege was limited to his own Facebook account, and it would be against the rules for him to bring a class action suit against the social media site, the Advocate General said.

Mr Schrems has been locked in a long-running legal dispute with Facebook, claiming the US tech giant collects more private data than is permitted under European Union law.

Because Facebook’s European headquarters is in Ireland, his legal actions in the past have involved Facebook Ireland and the Irish Data Protection Commissioner.

Today's non-binding opinion by the European Court of Justice’s Advocate General relates to a case taken by Mr Schrems through the Austrian courts, in which he claims that Facebook operates in Europe with contracts that are illegal under EU consumer law.

Facebook initially disputed the jurisdiction of the Austrian courts in hearing such a claim, so the Austrian supreme court referred the matter to the ECJ in Luxembourg.

Mr Schrems had taken action against Facebook Ireland in the Austrian courts for allegedly violating his own privacy and data protection rights and those of seven other Facebook users.

They had assigned their claims to his legal action after he invited Facebook users to do so online.

Those Facebook users are domiciled in Austria, Germany and India.

Facebook Ireland had challenged the international jurisdiction of the Austrian Courts and argued that Mr Schrems could no longer be regarded as an ordinary consumer because of his professional activities relating to his claims against Facebook.

The company argued that Mr Schrems could not, therefore, benefit from the privilege granted by EU law to consumers to sue a foreign company at home.

Facebook also argued that Mr Schrems’ Facebook page was effectively "professional".

The Austrian Supreme Court had noted that Mr Schrems specialised in IT and data protection law, and was writing a PhD thesis on the legal aspects of data protection.

The court said he had used Facebook since 2008, firstly exclusively for private purposes under a false name.

Since 2010, he had used a Facebook account under his own name, spelled using the Cyrillic alphabet, for his private use.

He used it for uploading photos, posting online and using the messenger service to chat. He had approximately 250 Facebook friends.

Since 2011, he had used another Facebook page, containing information about lectures, participations in panel debates, media appearances, books he had written, a fundraiser he had launched and information about the legal proceedings he had initiated against Facebook Ireland.

The court heard he had assembled a team of ten individuals, with a core of five, to support him in ‘his campaign against Facebook’.

The Advocate General issued an opinion saying that such activity did not deprive Mr Schrems of his consumer status under EU law, and thus his right to take legal action against Facebook Ireland on the basis of his private Facebook account.

The Advocate General said that consumer status depended on the nature and the aim of the contract, ie, Mr Schrems’ Facebook account, when it was agreed.

Only in "exceptional scenarios" could an ulterior change in the account’s use be taken into account.

If the nature and aim of his Facebook page was both private and professional, Mr Schrems could still enjoy his consumer status if the professional "content" was considered marginal.

The Advocate General held that Mr Schrem’s knowledge, experience, civic engagement or the fact of having become famous for his legal action against Facebook did not in themselves prevent him from being a consumer.

However, the opinion held that Mr Schrems’ consumer privilege was limited to the "concrete and specific parties to the contract" relating to his own Facebook account, and it would be against the rules for him to make use of this privilege for claims assigned to his case by other Facebook consumers in a class action.

This would give rise to claims being concentrated in one jurisdiction whereby class actions could seek out more favourable courts, by assigning all claims to a consumer domiciled in that jurisdiction.

The Advocate General said it could lead to "unrestrained targeted assignment" to consumers in any jurisdiction with more favourable case-law, lower costs or more generous jurisdictional aid, potentially leading to some jurisdictions being "overburdened".

Since 2011, Mr Schrems has fought several legal battles against Facebook, arguing that the company itself, and the ability for US intelligence agencies to access Facebook’s data pile, breached the fundamental right to privacy enjoyed by EU citizens.

In 2015, the ECJ ruled that the EU's main data transfer agreement with the US, Safe Harbor, was unfit for purpose, in a judgment based on a case brought by Mr Schrems’ through the Irish courts.

The full judgment on the case will be delivered in a number of months’ time. In 80% of ECJ cases, the court concurs with the Advocate General’s opinion.