Also, keeping it illegal protects a ton of jobs. The number of LEO,DEA,prison gaurds, judges,lawyers etc...employed. Those folks would be in serious trouble as the majority of drug related offenses are for pot. As a byproduct of that, if gives greedy politicians ammo for the propaganda machine. We won't even talk about pharmaceutical companies who rather synthesize it and make profits.
The income generated from the legalizing of weed would have to be substantial enough to override all that. Not to mention how many people would have to be pardoned from prison.
Sometimes the world we live in just doesn't make any sense.
They would not pardon anyone from prison as they were sentenced for breaking a law that was a law when they broke it and the most that they will ever do in the foreseeable future is to decriminalize personal possession and possibly turn a blind eye to allow shops to sell it like in Amsterdam.
Full legalization would as you say make them liable for millions of false imprisonment cases,they know this and would never fall foul of their own laws in this manner.
People seem to be under the misconception that weed is legal in Amsterdam but it is not,personal possession is decriminalized for small amounts and coffee shops are merely tolerated.
They imo anyway will not allow cannabis to be legalized as they know it will make people think in a new way that they do not like i.e.
Why are we destroying our planet,home?
Errr is it really ok to blow up millions of people and animals with nukes?
Why should we accept this?
Now i really think about it this doesn't seem to be right really does it?
Cant have the general public thinking deeply now can we,must feed them more alcohol to destroy their brains before they get any aspirations and refuse to carry the garbage for 200 dollars a week.
Also cannabis would create many new jobs and is a totally different market to that of silk,tobacco and cotton etc. than it was in the past.
The market had no room in those days for competition,nowadays there is plenty of room for cannabis in the market place as well as cotton,silk,beer,and tobacco and we now have a choice were we can purchase all of these items instead of being so poor we can only afford one or the other.