PrEP stands for Pre-Exposure Prophylaxis – a combination of two medicines (tenovir and emtricitabine, sold under the trade name Truvada) that greatly reduces the risk of HIV infection. It is a prescription drug taken daily by people who are at high risk of infection. According to the US Centers for Disease Control (CDC) the risk reduction is at least 90% for sexual transmission of HIV and at least 70% for injected drug use.

I’m in the UK at the moment and a big news story has been the dispute over who should pay for PrEP. The disputants were the National Health Service (NHS) and the local authorities. The NHS argued that it was a public health issue, so the local authorities should pay. The local authorities argued that they couldn’t afford it. The judgement came down against the NHS.

So what is there to get stroppy about? Well, it seems to me blindingly obvious that the cost of PrEP should be born by the individuals who need its protection. The pills cost GBP13 (USD17) per day. This is as much as five café-bought cups of coffee every day. That’s a lot of money, but I’d hazard a guess that a drug habit costs more. And for people at risk of sexual transmission, good old-fashioned condoms are a very affordable alternative.

This point was made in a Radio 4 interview with a lobbyist. She seemed affronted and said that it was not always practicable to use a condom every time one has sex. By way of elaboration she said that people were often too drunk to remember to use a condom. Finally, in words that could have been crafted to create maximum stroppiness, she said that if taxpayers declined to pay for PrEP they would be up for much higher expense to treat HIV-positive people. “That sounds like blackmail,” said the interviewer. The lobbyist disagreed.

Sometimes public policy should not be based simply on cash flow projections. Principles should come into the picture too. Every time a principle – the principle of personal responsibility, for example – is violated in favour of financial pragmatism it becomes harder to invoke that principle the next time.