Poll: Do you think the drink drive limit should be lowered and brought into line with Scotland?

If you take the southbound side of the road, on the English side of the border, you are perfectly within the law.

But if you take the northbound route, which comes under Wales, you face a 12-month driving ban and a possible jail term.

Sounds fanciful? Well at the moment that situation is purely hypothetical, as the drink-drive limit is the same on either side of the Wales-Shropshire border.

But as of today, that is exactly the situation drivers in the Scottish border town of Gretna will be expected to deal with.

New laws which come into force today mean that north of the Scottish border, the drink-drive limit is now 50mg of alcohol per 100ml of blood, compared to 80mg in the rest of the UK. This means it could potentially be an offence to drive after a single pint of beer.

For some years there has been talk about reducing the UK drink-drive limit to bring it into line with other European countries.

At the beginning of 1998, Tony Blair's Labour government produced a consultation document that recommended the reduction of the drink-driving limit from 80 mg to 50 mg, broadly speaking from two pints of ordinary strength beer to one. However, the proposal was never put into force, and the policy was officially abandoned in March 2002.

• The current limit in England and Wales is 80mg per 100ml of blood, which means that roughly speaking, around two pints of normal-strength beer or two small glasses of wine are enough to tip the average person over the balance, although it can depend on a variety of factors

• The 80mg limit is the highest in Europe, and is shared only by Malta

• A 50mg limit would mean that an average man would be limited to just under a pint of beer or a large glass of wine and women to half a pint of beer or a small glass of wine

• The Czech Republic, Romania, Hungary and Slovakia have introduced a zero-tolerance policy

• Germany has a 50mg limit, but for new drivers, the limit is zero

However, under its devolved powers of the Scottish government, the Holyrood administration has decided to go it alone and impose the new lower limit. Scotland's former Justice Secretary Kenny MacAskill said the Edinburgh administration did seek a joint approach with Westminster, but the UK Government decided to retain the current limit.

UK Road Safety Minister Robert Goodwill confirmed there were no plans to alter the drink-drive limit in England, although in May this year the devolved assembly in Northern Ireland announced proposals to reduce the limit.

A spokesman for the Welsh Government said as things stood, it was unlikely that Wales would be able to unilaterally reduce its own drink-drive limit without Westminster's say-so, although with the growing clamour for further devolution, it is not hard to imagine a situation in future when it might be able to do so.

Martin Bowen, a retired police chief who now works for Telford-based road safety group TTC, welcomes the Scottish government's initiative, and believes it is only a matter of time before England and Wales follows Scotland's lead.

He says the Scottish move will mean England, Wales and Northern Ireland are the only countries in Europe to have such a high limit.

"Other European countries are either 50mg or lower," he says.

"It can only be a matter of time before it is introduced here.

"The drink drive limit must be the same as the rest of Europe.

"It is all about saving lives. Research has shown that lowering the drink drive limit saves lives," adds Mr Bowen, who heads the drink-drive rehabilitation course for the Shropshire based road safety education organisation.

"In 2012, an estimated 230 people were killed in drink-drive accidents in the UK, accounting for 13 per cent of all reported road fatalities."

However, Hugh Bladon, of the Alliance of British Drivers, is not convinced, and firmly opposes any attempt to reduce the drink-drive limit across the rest of the UK.

"It is just a knee-jerk reaction by do-gooders and those who think the more you can do to restrict people, the better things will be, but it doesn't usually work out like that," he says.

Mr Bladon, who is himself teetotal, says he certainly does not condone drink-driving. But believes the new rules in Scotland will only create new difficulties.

"We believe that the current law in England is the correct one," he says.

"I think there are going to be a lot of problems in Scotland when the limit is reduced from 80mg to 50mg.

"A lot of people will run the risk driving the next day when they have been out the night before, and some people will think 'blow it, I'm over the limit now, I might as well have another'.

"The alcohol only really starts to kick in when the concentration level gets near 100, that's why the figure was set at 80," he says.

Mr Bladon says there is little evidence that reducing the limit would improve road safety, but fears it will have wide-ranging consequences for both the rural pub trade, and for individuals who inadvertently find themselves on the wrong side of a reduced limit.

"The thing is, somebody could go out believing they are legal to drive, they could lose their licence, and as a result they could lose their job," says Mr Bladon.

Should alcohol restriction be zero-tolerance?

A 2010 medcial review found "strong evidence" that someone's ability to drive is affected if they have any alcohol at all in their blood.

The current UK limit is 80mg per 100ml of blood – Europe's highest. Only Malta shares the same limit.

But Northern Ireland is considering making the same reduction as Scotland.

The Czech Republic, Romania, Hungary and Slovakia have introduced a zero-tolerance policy.

Germany has a 50mg limit – but for new drivers, the limit is zero.

Even those with a BAC (blood alcohol concentration) of between 0.02 (20mg per 100ml of blood) and 0.05 – people who would be within the new limit – are three times more likely to die in a vehicle crash.

So the potential new rules in Scotland aren't as strict as they could be. Sweden adopted a 20mg limit in 1990 and the number of drink-driving accidents fell.

A 1997 study on the change showed that a 20mg limit reduced fatal crashes by 9.7 per cent, with a 7.5 per cent reduction in all crashes.

They also found out that the lower limit reduced crashes among drivers who were the most serious drink-driving offenders.

So even drivers causing accidents who were found to be far over the limit reduced after the introduction of the ban.

The UAE is one of the few countries with a zero-tolerance policy for drink-driving

It seems obvious that the lower the limit, the fewer the accidents. But "absolute zero limits" – meaning anyone with a blood alcohol concentration above zero is driving illegally – are relatively rare.

Though generally, alcohol is removed from the blood at the rate of about one unit an hour, weight, sex, and age can all play a part. So can the amount of food or water consumed, medication taken, type of alcohol, metabolism and even stress levels.

Sir Ian Gilmore, chair of the Alcohol Health Alliance UK and special advisor on alcohol for the Royal College of Physicians said:

"I would say that zero-tolerance is the end point."