Ban? Bans rarely work. I would prefer something more effective. With guns there is something of a problematic issue with the 2nd Amendment. With currently illegal drugs, for example, I could see a licensing system put in place to allow for use. Something like this:
In order to use a particular drug like cocaine, heroin, or the like, you have to get a "drug abusers license." The license has a nominal fee for paperwork but is easily affordable. The license is public information--that is anyone can look up who's abusing drugs--and can be used as a reason to refuse to hire or terminate someone from a job. You agree in getting the license you are responsible for all debts incurred, including all medical expenses, resulting from your drug use.
Drug dealers and manufacturers are likewise licensed. The drugs involved are made to what is currently veterinary grade, again to keep the costs down and abusers are informed of that. That makes these drugs far safer than what they use now.
The abuser then goes to a licensed dealer, shows their license to abuse, and are sold the drugs they want to abuse. Dealers can also sell needles and other accessories for your drug abuse.
If you get caught outside this system--you are using without a license etc.--upon conviction you go to prison for decades on a first offense. The punishment is harsh to incentivize playing within the system. The disincentive is you need a public information license to use the drug and are now a "drug abuser." For many people this will be a huge problem. Since it would be hard to find anyone willing to sell you drugs illegally due to the penalty and the low cost of drugs in the legal system, you are pretty much forced into getting a license. Dealers and manufacturers will be all-too-willing to play by the system seeing legalization as safer and profitability as excellent within such a system.
For business and industry, knowing who's using and being able to deny employment or fire such a person means they can be more assured their workers aren't using meaning fewer drug tests, etc., lowering their costs. For many current users, being fronted off in public becomes a problem. They are faced with loss of status and employment if they continue to use.
Not perfect, but damn better than the current situation. Of course, that means you'd have to get your license to keep dropping LSD...