Big tech has crossed the Rubicon.
Facebook has suspended the sitting president of the United States, and Twitter has banned him permanently.
You don't have to like Donald Trump to find this terrifying.
You can be appalled by his campaign of lies against the result of a free and fair election. And you can be horrified by the storming of the Capitol carried out in his name. But you should be alarmed by the precedent this sets.
If the tech monopolies can deny a platform to the leader of the free world, then they can deny a voice to anyone.
Twitter's reasoning for the ban sets the tone for more censorship to come. It cites two tweets which broke its rules. One in which Trump says he will not attend the inauguration of Joe Biden and another in which he says "American patriots" will have a "GIANT VOICE" in the future.
The tweets are in the style we've come to expect from Trump. Neither incites violence directly, but in Twitter's view, they present a "risk" of incitement, because it fears they might be interpreted as an incitement to violence. "The President's statements can be mobilised by different audiences, including to incite violence," it says. There is simply no end to what could be censored following this chilling logic.
It used to be the Trumpist QAnon conspiracy theorists who searched for hidden messages in Trump's every utterance - now Twitter has turned this approach into its official policy.
The ramifications are global. Russian opposition leader Alexei Navalny has warned that Trump's permanent suspension will be exploited by the enemies of free speech. Whenever an autocrat wants to silence someone, he will say censorship is perfectly normal, even in liberal democracies.
Big Tech censorship has not stopped at Trump. It has digitally deplatformed those who have amplified his (false) claims of election fraud, too. In about a week's time, with the inauguration of Joe Biden, Donald Trump's party becomes the opposition. Will more politicians, activists and members of the public who question the legitimacy of the new administration meet a similar fate?
One of the more tedious arguments which is used to downplay the significance of tech censorship is that Facebook and Twitter are private companies. They can set whatever rules they please. If you don't like their approach to free speech you can set up your own platform.
But the fate of the alternative social-media company Parler - which Google and Apple have removed from their app stores, and Amazon has removed from its web-hosting service - shows there is no way around the tech monopolies.
The fact is that social media have become the 21st century's public square. To be denied a voice on these platforms is to be a digital unperson.
When the mega-corporations of Silicon Valley pick and choose which voices can be heard, they are no longer neutral platforms. Rather, they are exercising an extraordinary power over democracy. Their decisions are opaque and unaccountable, and yet are extraordinarily consequential. The censorship of Trump is just the beginning.
Fraser Myers is assistant editor of Spiked