Curbs planned on motorists who abuse prescription drugs Ministers will also end the anomaly which has seen drivers involved in fatal accidents while under the influence of drugs receiving lighter sentences than would have been the case had they been drinking. While the courts can take into account the amount of alcohol consumed when deciding a sentence, there are greater difficulties in doing so for drugs, where it is harder to calculate the amount taken and level of impairment. This was highlighted in the case of an eight month sentence handed to a driver who, having smoked cannabis, killed Lillian Groves, a 14 year old schoolgirl in Croydon, south London, last year. This provoked a public outcry and ministers have bowed to demands for a "Lillian's law" spearheaded by her family and Gavin Barwell, their constituency MP, who raised the issue with the David Cameron. "This is very welcome news indeed," said Mr Barwell, Tory MP for Croydon Central. When I raised this during Prime Minister's Questions, there was support from all sides of the house. If you look at the figures, the number of prosecutions for drink driving dwarfs that of drug driving, but if you speak to the police they say the problems are on a similar scale. A study by the Transport Research Laboratory estimated that drugs were a key factor in nearly a quarter of fatal road accidents and, according to Government-sponsored study in 2009, one young driver in 10 admitted getting behind the wheel while under the influence of illegal drugs. But despite the danger posed by motorists under the influence of narcotics, only 385 drivers faced drug tests were performed by police over Christmas, compared with 170,000 who were breathalysed. Successive Governments have grappled with the law on drug driving which under existing legislation is similar to that which applied to alcohol before the introduction of the breathalyser in 1967. It means that the police do not only have to prove the presence of an illegal drug but also that it impaired the motorist's driving. This normally entails making motorists perform a "Field Impairment Test" to demonstrate their coordination. Earlier this year the Department for Transport established a panel of technical experts to examine how to update the law to make getting behind wheel having taken an illegal drug an offence, which is likely to carry similar penalties to those imposed for drink driving, such as an automatic ban. The key task for the panel is to examine the levels of drug consumption which can be deemed to have caused impairment - effectively setting a limit for an array of narcotics similar to that which is already in place for alcohol. An AA spokesman hailed the move to tighten the law. "We would very much welcome the new offence," a spokesman said. However there will need to be a very careful examination of the detail especially regarding prescribed medication. Robert Gifford, executive director of the Parliamentary Advisory Council for Transport Safety, also welcomed the move. The important issue, however, will be for the police to continue to enforce those actions which we know already kill such as drink driving and driving dangerously.