PARIS — With a decision looming in a high-stakes lawsuit between Twitter and a Jewish student group in France, social media experts and lawyers are debating whether banning hate speech is an effective tool in the fight against anti-Semitism.

On Thursday, French judge Anne-Marie Sauteraud will decide whether Twitter must reveal information about users who wrote anti-Semitic tweets last year featuring the hashtag #UnBonJuif (#AGoodJew).

In October, the hashtag was briefly the third most popular label on French Twitter, in many cases used to mark anti-Semitic statements such as “A good Jew is a dead Jew.”

The Union of French Jewish Students (UEJF) sued the company soon after, demanding — along with four major French tolerance groups — that Twitter set up a system to warn users of hate speech, which is illegal under French law.

A key question in the case, said Marie-Andrée Weiss, an expert on French and American social media law, is whether the French court has jurisdiction over a US-based company. Twitter claims it does not.

“Even though Twitter’s attorney apparently argued that only a US court would have the power to compel Twitter to divulge who wrote the tweets, the French court is likely to claim jurisdiction, because the damage took place in France,” said Weiss, a lawyer based in New York.

‘If we are to track down every single user on Twitter who writes offensive comments, this will be endless’

Contrary to the US — where free speech can only be restricted when it leads directly to acts of violence — French and EU laws allow tighter limits.

“In France, one’s freedom ends where another person’s freedom begins,” said Merav Griguer, a Paris-based attorney and expert on Internet law.

“French law does not promote censorship, but instead bars abuses of free speech to protect other fundamental rights.”

Attempts at outlawing hate speech may strike Twitter’s American leadership as novel and invasive, but in many cases they stem from Europe’s — and France’s — historical mistreatment of Jews.

“Words can kill, and France is learning a lesson from its own history,” Griguer said. “Once, it allowed the spread of Nazism and anti-Semitism, which eventually led to one of the greatest crimes against humanity . . . Today, tweets such as ‘Death to Jews’ or ‘A good Jew is a dead Jew’ undoubtedly constitute an abuse of freedom of speech.”

In Europe, recent history has repeatedly played a role in legal rulings on hate speech, with EU member states given leeway to decide what’s out of bounds.

“EU law leaves it up to national courts to do their own analysis, case by case, and enjoy a certain margin of flexibility,” Weiss said.

She cited a ruling in November by the European Court of Human Rights that upheld a German ban on a controversial ad campaign by the animal rights group PETA.

The court ruled that Germany had not violated free speech laws by forbidding “Holocaust on Your Plate,” a publicity effort comparing the meat industry to the Nazi genocide.

The court determined that the case could not be detached from the German past, and that the country had a “special obligation to the Jews living in Germany.”

In a similar vein, “One could argue that France also has a special obligation to Jews living in France because of what happened under the Vichy government,” Weiss said, alluding to widespread collaboration with the Nazis.

‘Words can kill, and France is learning a lesson from its own history’

But even if French law sides with the Jewish student group, is outlawing hate speech an effective way of eradicating it?

“It’s a good thing that this case managed to earn national attention, and that the French government supported UEJF’s position,” said Jérémie Mani, the CEO of Netino, a Paris-based company that helps websites monitor content. “But if we are to track down every single user on Twitter who writes offensive comments, this will be endless. First anti-Semitism, and then what? Racism, homophobia, pedophilia?”

Mani cautioned the student union and other tolerance groups not to get “overly ambitious,” arguing that many #UnBonJuif offenders were merely young people acting out rebellious impulses, not genuine proponents of hate.

“The important thing is to strike the right balance between protecting freedom of speech on the Internet and avoiding the normalization of racism,” he said.

Weiss, who describes herself as “sympathetic to both parties” in the Twitter case, agreed that regulating tweets might not be the answer.

“Making anti-Semitic and racist speech illegal may, paradoxically, protect anti-Semites and racists, as they might [find] a more insidious way to propagate their hateful opinions,” she said.

“Racism and anti-Semitism have many faces, and by being able to read what people write, the government and non-profit organizations fighting such beliefs may find some explanation for the hate, engage in dialogue and educate.”