The European court of justice (ECJ) is set to rule on a landmark case over whether or not the so-called “right to be forgotten” can and should stretch beyond EU borders.

It will be the final step in a three-year legal battle between Google and France to determine how far the search engine should go to guarantee the privacy of European citizens who want their pasts to be wiped from the historical record.

If Google wins, France says, then the right to be forgotten becomes meaningless. This right, a function of an ECJ ruling from May 2014, requires the search engine to remove links to pages that “appear to be inadequate, irrelevant or no longer relevant or excessive … in the light of the time that had elapsed.” Even accurate data which was initially legally published can be removed, the court said, since it can “in the course of time become incompatible with the directive”.

France’s concern is that the right is only worth anything if it applies universally. Otherwise, the country has argued, a hypothetical complainant could find their past remains easily visible to American colleagues, or even a “geeky curious neighbour” who can simply fake their IP address to a non-EU country. So the French data-protection regulator, CNIL, has consistently fought Google’s attempts to limit the extent of the right, first to just Google.fr and other European Google domains, and then to any Google user based in Europe.

On the other side, Google argues that the extension of the right would pose a serious risk that other countries with more egregious limitations on freedom of speech would similarly attempt to universalise their restrictions. Thailand, for instance, might attempt to force Google to apply its lèse-majesté laws, banning insults against its king, worldwide.

The ECJ will be asked to detail whether or not sites have to delete links only in the country that requests it, across the EU, or globally. Photograph: Julien Warnand/EPA

“Since 2014, we’ve worked hard to implement the ‘right to be forgotten’ ruling thoughtfully and comprehensively in Europe”, Peter Fleischer, Google’s global privacy counsel, told the Guardian. “For the last 18 months, we’ve been defending the idea that each country should be able to balance freedom of expression and privacy in the way that it chooses, not in the way that another country chooses. We’re doing this because we want to ensure that people have access to content that is legal in their country. We look forward to making our case at the European Court of Justice.”

Over the course of its fight with France, Google has been racking up the bills: a November 2014 ruling from a Parisian court over the same issue threatened the company with daily €1,000 fines if it didn’t comply, while CNIL landed Google with a €100,000 fine in July 2015 for failing to comply with its own ruling.

It is technically this fine which Google is appealing all the way to the ECJ. It first appealed to the highest French court, the Conseil d’Etat, in May 2016. That court has now passed the key questions to the ECJ, which first created the right to be forgotten.

The ECJ will be asked to apply greater specificity to its initial ruling, detailing whether or not sites have to delete links only in the country that requests it, across the EU, or, as France desires, globally.

Google has already found itself with that burden elsewhere. In June, Canada’s Supreme Court ruled that Canadian courts do indeed have the right to force Google to remove links globally. “The internet has no borders – its natural habitat is global,” the court wrote in its judgment. “The only way to ensure that the interlocutory injunction attained its objective was to have it apply where Google operates – globally.“

In Canada, Google cannot appeal any further, but it may be able to apply for an alteration if it can prove that complying with the order would force it to violate other countries’ laws.