I agree, and am in favour of decriminalisation of marijuana, but I will present the argument against as I think it’s more nuanced than some people will make out.

Alcohol is a substance that is indelibly intertwined with our culture and rituals. Our socialising at bars, pubs and clubs; our celebrations (champagne!); and our meals (taking a bottle of wine to dinner with friends). Marijuana, by contrast, is in the UK a relatively new introduction. It doesn’t currently serve the same social function.

If each were to do the same level of damage and carry the same risk, it wouldn’t make sense to spend your political capital trying to ban alcohol (look at how prohibition turned out!) as it’s simply too deeply ingrained in our culture to try. But you could seek to prevent marijuana from reaching the same level of cultural necessity through stigma and criminalisation.

From a public health perspective, this would make sense; less cost to health services from related health conditions. So you don’t decriminalise, and at the same time take reasonable steps to try to reduce the harm to public health caused by alcohol.

Where I think this argument falls down is in the criminalising aspect. Does it truly prevent weed from reaching that status, and are your disincentives targeting the right people? To me it seems far more sensible to treat people as adults and educate them on the health risks of both alcohol and the devil’s lettuce.