Training in any athletic endeavor when you are impaired/under the influence of any mind-altering substance is potentially dangerous not only to the person, but to anybody who trains with that person.
I can not think of any cogent reason why any dojo should allow a person to train in an altered state. I have even spoken to a student who had alcohol on his breath, despite acting entirely sober. As the owner of a dojo, I am ultimately responsible for the well-being of the students training there. Clean body, mind and uniforms are simply starting points to walk onto my mats!
One of my sempai was going through a divorce and would smoke pot before training. Pot calms must people down. For him, it had a disinhibitory effect. The result was that he became an angry snap and people would get hurt (big strong person). This person needed to spoken to and told what was going on and that nobody really wanted to train with him anymore. This is a good person who was oblivious as to what was going on. He had no intent or desire to hurt anybody.
Train safe means NO MIND-ALTERING substances before training.
Thought I would give a response here as I like what you've said and plus you might find it amusing coming from me.(first impressions and all that)
Three points. Firstly from the view of letting someone train who has been taking drugs. If the person thinks it will make their training go better then let me explain what will generally happen so that others may look out for the symptoms. If the person not only has to train phsically hard but has to concentrate and correct themselves and stay centered and calm and yet alert and aware you will find they start feeling a bit nauseous. They will say they have a bit of a stomach problem(as an excuse) and if they are made to carry on in a disciplined fashion will start going red and white blotchy in the face. If they are made to carry on they will proceed to be sick and vomit.
Of couse the person will put on a good act and say it was the takeaway they had the previous night or some such excuse.
Secondly, a story. An old friend of mine got in touch with me over four years ago now and asked me to give him something to 'clean his system out' as he had been a heavy marijuana smoker for years and had an interview coming up in three weeks for a job on london transport where your blood is tested for such things.
I told him it would take heavy exercise, saunas if possible and a special nutritional programme to be followed to the letter.
Bless him he did it and completed it and got the job and and even progressed to inspecter. The point of this story though is what he told me afterwards.
He told me that he had always thought he was relaxed and only now did he realize that he wasn't relaxed he was LETHARGIC. He laughed at himself comparing how he was to how he felt now.
Thirdly for all those interested in mechanics. Marujiana destroys all the vitamin B1 in the brain, it is this which leads to the 'high'.
Vitamin B1 is the MAJOR food for the brain.
Alcohol has a similar effect by destroying the same vitamin in fact it was discovered way back in the 60's that if you injected bib doses of vitamin B1 into the blood of a drunk alcoholic they would sober up within a couple of minutes.
Hope this helps someone their musings on the subject.