Anyone who's ever come home from a night out with an empty wallet will groan at the thought, but David Cameron is to indicate support for putting a minimum price on alcohol today. During a visit to a hospital in the north-east, he will say that excess consumption of alcohol is costing the NHS £2.7bn a year. This comes ahead of a government strategy on alcohol, due to be published soon after nearly a year of consultation with health professionals and the drinks industry.

If minimum prices are endorsed, it will mark a change in the government's policy. Cameron is instinctively opposed to further regulation, while the public health minister, Ann Milton, has queried whether it would be legal under European free trade legislation. Scotland, which has gone furthest on prices, is still testing the legality.

Of course, minimum prices will have the greatest impact on supermarkets and shops, where discount selling is more common than in pubs or bars. But is it an effective way to reduce dangerous drinking and alcohol-related problems?

Minimum prices would have most effect on the cheapest, strongest end of the spectrum, substantially upping the price of budget ciders (like the notorious, discontinued White Lightning). Some of these could more than double in price. For this reason, it has gained the support of a wide range of health campaigners: upping the prices of these drinks could target the most problematic drinkers.

Over at the BBC, Branwen Jeffreys explains some of the evidence cited by those in favour of the move:

Those who support a minimum price say there is strong evidence internationally that price is linked to consumption, and higher consumption is linked to higher harm. They point to Finland where in 2004 a dramatic cut in prices via taxes led within a year to an increase of 9% in consumption, according to official figures.

Most alcohol in Finland is sold through tightly controlled government-run shops. By 2005 alcohol-related problems were the most common cause of death among Finns of working age.

A 2008 model by the University of Sheffield suggested that a high enough minimum price could significantly reduce the impact and cost of alcohol to society. It found that problem drinkers seek out the cheapest ways to get drunk as they tend to be either young or those who drink a lot, and therefore would change their behaviour in response to price increases more than moderate drinkers would. (It has been strongly challenged by the drinks industry).

While the international examples may be compelling, it is worth pointing out that minimum prices have not yet been introduced in a country with a history of few limitations on the sale of alcohol. States in Canada which have used minimum pricing have a history of prohibition, and the Nordic countries have a tradition of selling alcohol through government-owned shops. That's why the example of Scotland will be watched closely.

On the other hand, some question the efficacy of minimum pricing on economic grounds. Tim Harford points out that it would up the profit margins of supermarkets -- and that in fact, if they decided a minimum price amongst themselves (rather than having one imposed by the government), they would be in breach of competition laws. He recommends increasing taxation further instead, as this would ensure that prices rise in proportion and would put the extra revenue in the hands of government rather than supermarkets. Rather paradoxically, minimum prices could make cheap alcohol a very lucrative product for supermarkets (because of the mark up).

Although the long-term benefits to society are difficult to prove conclusively, most people would agree that less cheap alcohol would have a positive effect. The evidence that alcohol consumption goes down when prices goes up is fairly strong. The best economic method of doing this remains to be seen.