§ Mrs. René e Shortasked the Minister of Transport (1) pursuant to the Secretary of State for the Home Department's reply to the hon. Member for Wolverhampton, North-East on 16 July, what data are available to indicate at what cannabis level a driver becomes a hazard on the road;
(2) pursuant to the reply of his right hon. Friend the Home Secretary to the hon. Member for Wolverhampton, North-East on 16 July, 296W what research has been carried out to determine the level at which a person's driving judgment becomes impaired through having cannabis in the blood.
§ Mr. Kenneth ClarkeThe Transport and Road Research Laboratory is carrying out a survey of the extent to which drivers involved in accidents have previously taken drugs, but this work is not designed to produce quantitative evidence of the effect of any particular drug on driver behaviour. I am not aware that any data of this kind are available in respect of cannabis. The general provision making it a statutory offence to drive, or be in charge of, a vehicle when unfit to drive through drink or drugs does not, of course, prescribe a maximum legal limit.