John Hemming was probably right when he told the House of Commons last week that it would be impractical to lock up everyone who re-tweeted information about a famous footballer’s alleged affair (and the resultant anonymised injunction), but that should be no cause for celebration. Those Twitterers were in open contempt of court, and violating a legal structure which allows a rare opportunity for privacy and the public interest to be weighed against each other. Before, injunctions might have played a role in restraining the worst impulses of the traditional media. This week’s developments demonstrate that the floodgates have been opened, with deeply troubling implications for privacy.

Let’s be clear: far from a victory for freedom, this is a triumph for that particularly insidious form of fascism, that vampiric impulse which compels us to pry into, disapprove of and ultimately ruin the lives of people we’ve never met in order to extract a few minutes of titillation from them. The fact that somebody is famous by no means gives us ownership over all the details of their lives. Public humiliation may not break the skin, but it can be as painful and traumatic a process as any physical assault, and should not be inflicted for trivial reasons.

Apologists for intrusion might claim that entering “public life” means that you must accept that your privacy will be curtailed. Beyond the basic flaws in that argument (which has little to say, for instance, about the family members of celebrities, who have no choice over their intimate secrets becoming coffee-break conversation) lies a deeper question: is that really the kind of bargain we, the public, want to strike? Do we want fame, and the power it bestows for shaping our culture, to be granted only to those sufficiently pathological to be willing to give up every last detail about themselves and their loved ones for the entertainment of the public? I hope not.

Obviously celebrities will sometimes want to suppress information where it is in the public interest that that information be released, and there is certainly room for debate about the implications of injunctions for freedom of speech. But being interesting to the public is not the same thing as being in the public interest, and the behaviour of the Twitter crusaders in the past weeks does not suggest that they are sufficiently capable of making that distinction to justify their putting themselves above the law.

If anything is fair game, and if Twitter users cannot be stopped, the dangers are clear. Privacy is more than an abstract noun – everyone needs to have parts of themselves that aren’t subject to the scrutiny of every voyeur, bigot or gossip that who takes an interest in them. Having some control over the face you present to the world is vital if you are to have meaningful social relations in different contexts. When Twitter users become a law unto themselves with the co-operation of MPs and the news media, we risk losing an important freedom, and one that may prove very difficult to win back.