In my experience all too many cannabis users smoke to utter intoxication. Like binge drinkers they aren't satisfied with a bit of moderate mellowness, they have to get completely off their faces on the product of what appears to be a THC arms race. Gone are the days of the gentle stoner... all too often users are also binge drinkers etc etc, and as Drago says, just as likely to kick off as anyone else. Skunk doesn't make you all creative and mellow like a nice sticky bit of black or even some of the greener leb we used to see back in the halcyon days of moderate consumption, I can only associate it with a much darker side of society than the resin smokers I knew at Uni.
 
A really good mate of mine is a lifelong stoner. It really, really saddens me to watch a creative, intelligent, likeable guy ruin himself by smoking till he pukes, day in, day out. Born with a silver spoon in his mouth he can't hold down a job, relies on his Dad to bail him out time after time after time.
		
		
	 
 
This is about as accurate as it gets IMO.
 
I smoked weed/black on and off for around 15-20 years and noticed a definite change in the type of person involved with the culture. It was once a mellow thing to do, a few beers, an esoteric chat, put the world to rights and have another hash cake and ain't the music good, who is it? That kind of thing.
 
Enter the skunk era - weed grown under hydroponic conditions that has never seen sunlight and you have some crazy stuff, generally smoked by those crazy enough to get that high, confused and generally wasted. The intensity of the stuff is horrible compared with a gentle bit of grass, or solids like pollen, charis etc And with that, down goes the behaviour with it.
 
But, the problem insofar as the law is concerned is that there was very little distinction and you were more than likely to feel the heavy hand of the law when cannabis smokers 
were the mellow hippies they once were. And what I mean by that is dealt with more severely than the average binge drinking twerp in the typical English city on Friday/Saturday nights. Glass in the face? Not a problem, we see it week in and out and we're so used to it on the beat we forget that alcohol related violence is a much bigger problem 
still than drug related violence,  and that it is far more dangerous also than cannabis.
 
...alcohol caused 40,000 deaths per year compared with 1 from marijuana
https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CDUQFjAB&url=http://www.bbc.co.uk/sn/tvradio/programmes/horizon/broadband/tx/drugs/survey/&ei=Uzz1UKjPO-HJ0QXeiIGIDw&usg=AFQjCNE-mQCOLy7K5hYZUaksBYyeaDx2fQ
 
...there are some other interesting facts regarding the situation in the US where the attitude toward cannabis has a far more virulent streak, even confronted with the same facts here - that most violence on the streets is caused by alcohol.
 
https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CEQQFjAB&url=http://www.saferchoice.org/content/view/24/53/&ei=cT31UM2sN-KR0QXj9oDACg&usg=AFQjCNG5bgKsvAkKj-58CpXTeYoSDwHwAQ
 
Not exactly neutral I know but they seem to have backed up their assertions unlike the anecdotal ones on this thread from those who should know better.
 
A big problem with cannabis insofar as the authorities are concerned was its association with a way of thinking - it was considered subversive as it altered one's mind. This is, I contend one of the reasons why cannabis has always been given a bad name and has also in the present confused the issue at a time when some cannabis - skunk - is actually very problematic and anti-social, clouding judgment on both sides. In the same way as the police have recently wasted their resources trying to nail peaceful environmental activists, for a long time before the advent of skunk which perhaps does require some form of control, the police went to inordinate lengths to repress cannabis and its associated culture, not because it represented any real threat like Greenpeace, but because it was political. The Battle of the Beanfield and the police assault/vandalisation of travellers and their homes is one of many incidents that springs to mind as well as much of the inner-city rioting that took place in the early eighties, being the result of heavy-handed stop and search (for cannabis) in the black community.
 
So, unfortunately, the police position regarding cannabis has always been politically charged and as a result I would contend, fairly worthless barring the admissions from top ranking police officers regarding the futility of prosecuting for use of the drug.