In the war for control of the internet, the potential significance of Telegram founder and CEO Pavel Durov’s arrest is difficult to overstate.

At the heart of French authorities’ case against the Russian-born billionaire is an enormously consequential question: are online platforms legally responsible for the speech of their users?

Prosecutors say Durov was detained as part of an investigation involving 12 criminal allegations, most of them related to “complicity” in serious crimes ranging from drug trafficking to the distribution of child sex abuse material.

While governments around the world have for years sought to exert greater control over online speech – cracking down on everything from racial hatred and internet bullying to “misinformation” about the COVID-19 pandemic – the arrest of a tech founder by a liberal democracy has few, if any, precedents.

Perhaps the closest parallel is the case of Facebook executive Diego Dzodan, who was arrested by Brazilian authorities in 2016 over the tech company’s alleged refusal to hand over WhatsApp messages related to a drug trafficking investigation.

Dzodan was released after nearly 24 hours in custody after a judge ruled that his detention was “extreme” and amounted to “unlawful coercion”.

The argument that tech companies should be held criminally liable for the activities of people who use their services is, at best, tendentious.

A less generous view would be that it is nonsensical.

Car companies, for example, are not considered responsible for drunk drivers or bank robbers using their vehicles to flee.

Many of the issues at the heart of the debate were in fact largely settled decades ago in the United States, the birthplace of the internet and the home of many of the world’s most influential platforms.

The Communications Decency Act, passed in 1996, provides broad immunity to internet providers for the content that they host out of a recognition that a free and open internet could not exist otherwise.

Others are sceptical that a hands-off approach to moderation is a reasonable excuse for avoiding responsibility.

Timothy Koskie, a postdoctoral researcher at the School of Media and Communications at the University of Sydney, said that moderation of one kind or another is fundamental to the existence of every platform.

“If I were to touch that analogy of the car, I would say the question is the extent to which the taxi driver is complicit in giving a ride to the bank robber,” Koskie said.

While other countries have less robust free speech protections than the US, even governments that have significantly tightened the reins on platforms have been forced to back down from more extreme proposals.

The European Union, which introduced comprehensive regulations to tackle online harm with the Digital Services Act in 2022, in June cancelled a vote on proposals to mass-scan encrypted messaging apps for child sex abuse material after critics likened the measures to George Orwell’s 1984.

Unsurprisingly, Durov’s arrest has sent a chill through the tech scene, where libertarian ideals about free speech and privacy are widely championed.

Many tech entrepreneurs and internet freedom advocates argue that Durov’s arrest sets a dangerous precedent and have called for his release under the hashtag #FreePavel.

Andy Yen, the founder of Switzerland-based email provider Proton Mail, described the criminal case as “insane” and suggested that tech founders may no longer be safe to travel to France.

“This is economic suicide and is rapidly and permanently changing the perception of founders and investors,” Yen said in a post on X.

Rumble CEO Chris Pavlovski, whose video platform has positioned itself as an anti-censorship alternative to YouTube, said he had “safely departed” Europe.

“France has threatened Rumble, and now they have crossed a red line by arresting Telegram’s CEO, Pavel Durov, reportedly for not censoring speech,” Pavlovski said on X.

“Rumble will not stand for this behaviour and will use every legal means available to fight for freedom of expression, a universal human right.”

Some commentators have also questioned why Durov has been singled out when other platforms host harmful content.

X owner Elon Musk, who has called for Durov’s release, claimed that Meta CEO Mark Zuckerberg had been able to avoid the glare of authorities because of his willingness to censor content and share users’ data.

While self-avowed libertarian Durov is on record as being suspicious of state control,  the characterisation of him as a free speech warrior among a crowd of government lackeys sidesteps an important distinction between Telegram and other platforms.

Unlike WhatsApp and Signal, Telegram has access to most of the content shared by its users as it does not use end-to-end encryption by default.

That means that Telegram can share information with authorities to an extent that is not true for some of its competitors.

Potentially, that makes the platform an easier target for authorities frustrated over the tech sector’s perceived lack of cooperation with law enforcement.

Questions have also been raised about the geopolitical implications of the case against Durov, who left Russia in 2014 after refusing to silence opposition groups on the earlier VK social network.

In Russia, both allies and critics of Russian President Vladimir Putin have called for his release in a rare alignment between political foes.

The French government has sought to dispel any suggestion that Durov’s arrest is politically motivated or at odds with civil liberties.

“France is deeply committed to freedom of expression and communication, to innovation, and to the spirit of entrepreneurship. It will remain so,” French President Emmanuel Macron said on Monday.

The success or otherwise of those assurances may hinge on what happens next.

After a maximum of 96 hours in custody, Durov must either be charged or released on Wednesday.

Koskie said there are a lot of unknowns about the case and how “idiosyncratic” the underpinning legal theory may be.

“It could be that, within the investigation, there is a much more personal tie to the situation than exists at any other platform, in which case this organisation has simply crossed a line that no other platforms have, but the line was always there,” he said.