If I spot a driver with a cigarette in his mouth I try to give him a wide berth.

There’s some evidence I read somewhere that drivers who smoke are more likely to have accidents – though this may also be because (in my prejudiced observation) they are more likely to be driving poorly maintained battered white vans.

Now, the British Medical Association (BMA) have added to the charge-sheet against drivers who smoke.

It’s so dangerous, they say, that though you are the only person in the vehicle it should be a criminal offence to light up.

The concentration of toxins is 23 times higher than in a smoky bar.

I’m the former Home Secretary and Justice Secretary, who is not exactly regarded as soft.

I did introduce some new criminal offences – and lengthen sentences on others.

Tougher enforcement and punishment does bring down crime.

But even for me the BMA’s proposal is, frankly, over the top.

Some new laws are easy to enforce. The ban on smoking in public places – clubs, pubs, and restaurants included – is a good example.

Much to my surprise there’s been an astonishing level of public consent to this law change. There have scarcely been any breaches or prosecutions.

But watch passing traffic for any length of time. I guarantee that you’ll spot at least one driver using their mobile phone.

Seeing drivers texting whilst driving is not unusual.

That really is dangerous. It’s an offence. But it goes on because it’s not easy to detect.

Our police have more important things to do, not least at a time when the resources available to them are being reduced.

I’m profoundly uneasy about making the smoking of a cigarette in the private space of an individual’s car into a criminal offence. It’s disproportionate.

Virtually every smoker I know would like to give it up.

These days they do treat non-smokers with great respect.

The better way to cut down on the number of drivers who smoke is by education, not the criminal law.