There are about 1.5 million people driving on Britain's roads without insurance. Every year they maim and kill thousands of other motorists, costing the insurance industry around £500 million and adding an average of £30 to every driver's annual insurance premium. From Monday, for the first time, it will be a criminal offence to cause death while driving a vehicle which is unlicensed or uninsured, or when disqualified. It is about time (see page 15)

The present law is ludicrously lax. A car can be a lethal weapon and all too often those causing accidents are drivers who have no right to be on the road. Catching and stopping them, however, is proving very difficult. If a car is never registered, there is no computer record at the Driver and Vehicle Licensing Agency in Swansea.

Anyone renewing a tax disc has to show a valid insurance certificate; the presumption is that unless application has been made for a statutory off-road notification (Sorn), car owners who do not renew their tax disc are breaking the law. But there are no records of the thousands who drive old unroadworthy vehicles, untaxed and uninsured and, being untested, inherently dangerous. Random police numberplate scans pick up thousands each year. But for most, the first time their car enters official records is after a crash.

What is especially scandalous is the high number of people still driving while uninsured and the falling level of fines. In 2006 some 263,000 drivers were convicted, compared with 255,000 in 1997. But the average fine paid fell 17 per cent, from £224 in 1997 to £185 in 2006. Payment has become ever harder to enforce: those caught - petty criminals, illegal immigrants, young and reckless drivers - often have no job, no money and no fixed address and magistrates have despaired of levying penalties that cannot be collected.

The law needs to be far tougher. The section of the Road Safety Act 2006 that takes effect on Monday will at least end the absurdity of magistrates needing proof of dangerous driving before they can enforce criminal penalties on uninsured drivers. From next week, a charge of driving while uninsured, unlicensed or disqualified can go before the Crown Court and incur a maximum sentence of two years' prison. Statistics show the need: in 2000 160 people died because of an uninsured driver; that figure had risen to 208 last year, despite a general fall in road deaths.

Police already have the power to seize and crush old, dangerous and unlicensed cars - a power used too infrequently. Because of the rising cost of learning to drive, passing a test and registering a vehicle, more and more people have been tempted to ignore all the laws on registration and insurance. Their fatal recklessness must be stopped. Keeping a car on the road is, admittedly, expensive - partly because the uninsured put up all insurance costs. Keeping potential killers on the road costs far, far more.