Legality isn’t an excuse for impairment. If you drive with medical cannabis,...

https://atomic-wiki.win/index.php/Can_a_Specialist_Doctor_Prescription_Protect_Me_From_Prosecution%3F

Legality isn’t an excuse for impairment. If you drive with medical cannabis, you must meet DVLA fitness standards and stay under the 2mcg/L THC limit. A medical defence helps, but your primary duty is ensuring you are fully safe behind the wheel.