Facebook has finally been dragged to testify to politicians in Washington and London, and there is now a global consensus that something must be done about powerful internet platforms.

Not only has Mark Zuckerberg taken up semi-permanent residence on Capitol Hill, but next week senior Facebook officials will appear before the House of Commons fake news inquiry, whose chairman, Damian Collins will attempt to unpack what went wrong in the entanglements between Facebook and Cambridge Analytica, and whether these have facilitated the hacking of western democracy. And the House of Lords has opened an inquiry on internet regulation. Within months, the debate has shifted from “you can’t regulate the internet” to how, and by whom, internet platforms should be regulated.

Everything is suddenly on the table. Following concerns about hate speech, fake news and child exploitation, the culture secretary, Matt Hancock, recently spoke about reviewing Facebook’s liability exemptions. For Facebook et al this innocuous phrase is dynamite: taking away protection would mean platforms bear legal risk for content posted by their users, and should monitor it. The European parliament is considering altering the copyright regime against them, and in favour of news publishers. Fanned by the newspapers – who after all have had their lunch eaten by Facebook – it must look to Zuckerberg from his Silicon Valley bunker that the policy juggernaut is careening out of control.

Of course, he had it coming. Like sorcerers’ apprentices, platforms are powerful in part because we made them so. In the past two decades, governments around the world have looked to them to solve the social problems they host. Giving them responsibility to ensure protection of children – or guard against hate speech, copyright infringement, and now fake news – also makes them all-powerful over online rights, with no oversight or appeal. As our lives have moved online, so platforms have become adjudicators of our fundamental rights, even in the process inventing the “right to be forgotten” – or rather the right to be de-listed from Google results.

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Parliaments and governments around the world have multiple levers they can use in their unfolding negotiation with Facebook. They can use the tax system: the problem is that we do not have a sense of whether Facebook is more like the alcohol and gambling industries – which are considered a social bad and taxed accordingly – or a social good and subject to tax breaks.

They can use the competition law regime: how about tweaking the Enterprise Act public interest regime, or equivalent European laws, to stop platforms growing or buying up their competitors – unless they meet societal standards of transparency and public interest?

One of the things the Lords are grappling with is why competition law has failed to prevent their dominance. The truth is that the social objectives of competition law have been lost: if the price is right, the competition regulators have, until recently, been happy. This is why the Lords have to think not only about which tweaks are going to deal with the issue, but about how to act: whether we are deciding to break up Facebook or to regulate it in the public interest.

If we are setting out what the public expectations of platforms are, and what regulatory deals it will get in return, that is bigger than a select committee inquiry can deliver. If this is essentially a negotiation, it means talking softly and carrying sticks with care: sticks that include tax, liability and competition. If regulators and parliaments around the world are to use such threats, they need to do so advisedly and credibly. And they must also do so sparingly: this is after all an issue of media freedom.

• Damian Tambini is co-editor of Digital Dominance: The Power of Google, Amazon, Facebook and Apple