Prescribed cannabis is legal, but road safety rules still apply. You must stay...

https://wiki-legion.win/index.php/If_I_Get_Pulled_Over,_What_Do_I_Say_About_My_Prescription%3F_A_Guide_for_Medical_Cannabis_Patients

Prescribed cannabis is legal, but road safety rules still apply. You must stay under the 2mcg/L THC limit and meet DVLA fitness standards. A medical defence exists, but it’s not a safety net