Driving with prescribed medical cannabis involves more than just holding a...

https://star-wiki.win/index.php/What_Does_the_Medical_Defence_Actually_Cover_for_Cannabis_Patients%3F_A_Guide_for_Drivers

Driving with prescribed medical cannabis involves more than just holding a prescription. While a medical defence exists for the 2µg/L THC limit, it isn't a free pass. Drivers must notify the DVLA and remain fully fit to operate their vehicle