Facts. (a) Chloe smoked cannabis at 11pm and drove at 8am. (b) Aisha (Scenario 13) drives after taking her medicine as prescribed.
What the law says.
- (a) Over 2 µg/L is a s.5A offence. There is no impairment test and no "safe" time can be given.[46]
- (b) The statutory medical defence in s.5A(3) applies if the drug was prescribed and taken as directed. Once raised, "the court must assume that the defence is satisfied unless the prosecution proves beyond reasonable doubt that it is not".[47] But s.4 still applies: "it is illegal to drive, with legal drugs in the body, if this impairs an individual's driving ability" (APCDLO guidance).[7]
Escalation. Collision, child passengers or a professional driver: heavier penalty and wider consequences. Penalties as in Scenario 2.