To ban something is to insist that people want that thing, wish to undertake that activity. After all, if the impulse to indulge were zero then there would be no point to the ban, would there? The incidence of the activity would be zero both before and after, in the presence and the absence of the ban. No one goes around virtue-signalling by insisting that no one do what none has the slightest intention of undertaking.

OK, that might not be true of entirely all politics but as a guide to logic it is still sound.

If people wish to do something then why shouldn’t they do so? This is the hurdle that any proposal to outlaw an activity must clear. What is the justification for snatching away an opportunity for people to make their own lives better, by their own lights?

That some such restrictions leap the barrier is obvious. The existence of murder shows that some do indeed wish to do it. We ban it as best we can, punish it if we’re able and generally try to discourage it. We don’t succeed, as some hundreds in the UK find out every year, but we do try.

That some don’t leap the barrier is equally obvious. History is replete with sumptuary laws in which what one may wear or eat is determined by government – on the grounds that the peons should not be allowed what is properly, righteously, something that only the elite may be able to do. The differentiation between those emitting carbon by flying for a holiday and those doing so to attend a climate demonstration (copyright Emma Thompson) is perhaps a modern incarnation.

We need therefore a rule we can use to test when a ban is righteous. J. S. Mill provided one variant of this: the right to swing the fist is absolute until the nose of another is met. In more modern jargon we call this a third-party cost.

There are costs and benefits to everything. When consenting adults are gaining the one and bearing the other, there is no justification for limiting the activity. But when the effects spread to those not volunteering to partake then there are costs to third parties.

This does not mean that a ban is justified, only that is a necessary – but not sufficient – condition. Only in the presence of those third-party costs can we then go on to consider the rest. Would a ban work? Would it be commensurate? Is the harm too trivial to justify government action? And so on.

My IEA paper, To Ban or Not to Ban, walks through this decision tree and finds that all too often the hurdle isn’t leapt.

Take, for example, the famed case of the chlorine-washed chicken. It is widely insisted that its import from the United States simply cannot be allowed. For no one wants it – we Brits demand higher animal welfare and food preparation standards than that. We can quibble a bit over how our own salads are already prepared and accept that there’s no actual or direct harm to us in its consumption. But it’s the deeper logic which really illuminates.

The ban is an admission that Brits – some portion of them, some of the time – actually desire chlorine washed chicken. There would be no point to an import ban if people wouldn’t buy it. The very call is to prove that there is domestic demand for the product. And if people want it then why shouldn’t they have it?

Is there a third-party harm here? No. Those who want non-washed gallus gallus can still have it, so no harm is being done to those who are not party to the decision to consume the American product. A ban is not justified.

Which gives us our test for any and every proposal to limit behaviour. That it’s bad for those doing it is not enough. Only those things which pass the third-party harm test may be righteously banned or limited. To do otherwise is to limit the rights to a better life, by their rights, of those who would undertake that activity which harms no one else.