Parents Gary and Natasha Groves on anti-drug driving campaign
7 May 2012 Last updated at 10:29 BST
Drug-driving in England and Wales could become a specific offence, with a potential jail term and fine, under a new law expected in the Queen's Speech.
Police currently have to show driving has been impaired by drugs to prosecute. But under the plans, it will automatically be an offence to drive with certain controlled drugs in your body in excess of specified limits.
Gary and Natasha Groves spoke to BBC Breakfast about their campaign against drug driving after their daughter Lillian was killed by a driver who had smoked cannabis.