Good idea. Dont think there needs to be limits warren like there is with beer. Most drugs are illegal and certain prescription ones say not to drive or operate heavy machinery. If you get caught even a tiny bit under the influence of illegal drugs then and 12 month ban is in order I think. Eg Weed. Coke . Speed. ketamine . Extacy etc etc. With regards to prescription drugs if the doc or the instructions tell you not to drive and you do then thats your fault too and deserve 6 points and a fine perhaps