I have experience with the substances mentioned in this topic. Funnily enough I stopped drinking completely soon after getting the ebike. Out of all of the legal and illegal drugs alcohol is one of the worst. I imagine some medications will also drastically alter the way that one may drive/ride. To be honest the change I've seen in people when they are drunk is terrifying. The hangovers can last well into the next day, and even the day after, and the effect on the body is negative. As for crack/smack if the person injects it they have even higher risks of overdosing, sites getting infected and hepatitis, HIV and AIDS. They are also extremely addictive and expensive and you meet awful people on the journey to score more class As. As with alcohol I think they're a complete waste of time and money and not worth the health risks. 1 hour between spliff and riding though if you can handle it!A lot is made of drinking and driving, and more recently drugs and driving , but to be perfectly honest either in combination with cycling is surely just as dangerous for the individual on the bike - and potentially others too. All the same reflexes are needed for cycling. Don't know if there are any specific rules about this but you never hear much about it. "Furious cycling" is I think an offence - and I am informed that contrary to popular belief you can be done for speeding on a bicycle (albeit the lack of a number plate makes it harder to prove who it was).
It amuses me that people who don't drink and drive think it's OK to cycle to the pub and back for a couple of pints. With the strengths of many beers sold these days, they would fail a roadside breath test without much doubt - but share the road with other road users in exactly the same way.
Personally, I'm even less happy about getting on a bike after having a drink (or the next morning after having a few) than getting behind a steering wheel. Perhaps it is an increased awareness of one's vulnerability on a bike without a metal comfort cage for protection. Got no car at the moment anyway and since deciding to cycle everywhere instead I stopped drinking completely. That's not a response to any rules - just prefer it that way.
On the other end of the spectrum, a friend I've known for many years does still go partying regularly at the weekend, consumes cocktails of recreational substances (each to their own and all that)but drives a lorry during the week and does suffer the odd bout of occasional 'rage' . Makes me go a bit cold to be honest. As far as pot is concerned, effects on reflexes are very long lasting (as are detection times) and many people smoking it do it daily or a few times a week. Can't see how that is a natural fit for safe cycling - or driving - to be fair.
More worrying is that I've seen some sober people have less control of their chosen vehicle than those under the influence!