I am not clear how there is a causal link between the two. Are you saying that legal weed/shrooms causes crime to go down? Or are you merely pointing a correlation?

Anytime you make something that people like to do legal, crime will go down as those people aren't criminals anymore. And a lot of people do weed. It's directly causal. More importantly, you destroy a huge profit center for organized crime, weed is one of the big cash crops.

It seems obvious that if drugs such as cannabis are held to the same standard as decidedly more deadly, legal, drugs such as tobacco and alcohol, then the accompanying crime statistics are bound to be less.

Pot heads aren't known for their violent tendencies, as compared to alcoholics.

It's quite obvious that when you decriminalize something, the crime rate will go down, since the people doing that thing are not criminals any more. (n / m) < (n - 1) / m.

But even apart from that (because it's a cooking-the-books level trick, really), decriminalization of drug use has other effects that lower crime rates. For example: keeping up a heroin habit is hard when you need to pay black market rates (€100 / $150 per day). So often, these people need to resort to burglary, robberies or prostitution. Regulating the market drives the prices way down (you could have retail prices for a brick of coke that are the same as that of a package of coffee if you'd let the market work unrestrained), which causes people to not have to resort to crime to fund their habits.

(note: not advocating unregulated heroin or cocaine markets, just stating the obvious socio-economic implications of prices within the bounds of affordability for regular people with a regular job, leaving aside their ability to do said job)

> (n / m) < (n - 1) / m.

Looks like you got that reversed

Whoops you're right - I meant (n - 1) / m < (n / m).

Making the use of marijuana legal means that there is no longer the crime of 'using marijuana'. You can't get a more direct causal link than that.