Google clashed with France in a top EU court on Tuesday arguing it feared for freedom of speech if forced to apply Europe's "right to be forgotten" principle worldwide.
"The court is hearing a wide range of testimonies today, which is highly unusual for a case like this," said a legal source at the European Court of Justice in Luxembourg, on condition of anonymity.
The two sides are battling over a shock 2014 decision at the same court, that imposed a right for individuals, under certain conditions, to have references to them scrubbed from search engine results.
The US tech giant firmly opposed the decision, but complied with the ruling by delisting search references once requested across its European domains, such as Google.fr or Google.de -- but not Google.com or domains outside the European Union.
France's data regulator, the Commission Nationale de l'Informatique et des Libertes (CNIL), opposed the distinction and said the firm should apply the delisting to all extensions, regardless of the national domain name.
In 2016, CNIL fined Google 100,000 euros ($112,000) for non-compliance and Google appealed the case to France's highest court, which in turn has referred to the ECJ for an opinion.
Google argues that its application of the right to be forgotten is already effective in France for well over 99% of searches.
It also adds that the company has imposed geo-blocking technology for EU searches that attempt to use non-EU domains to access de-listed information.
Lawyers for CNIL believe that a global implementation for the EU's "right to be forgotten" is the only the way to ensure European rights are upheld.
On Tuesday, EU court judges heard a long list of stakeholders, including lawyers from CNIL, Google as well as representatives from human rights groups that fear abuses of the EU's "right to be forgotten" rule by authoritarian states outside the bloc.
"If European regulators can tell Google to remove all references to a website, then it will be only a matter of time before countries like China, Russia and Saudi Arabia start to do the same," said Thomas Hughes, Executive Director of ARTICLE 19, a rights organisation.