After watching a bunch of videos of riots I think its important to explore the perception of a riot from the view of a police officer.
Let us consider this, your a police officer, you have been on duty for the past 12 hours because riots are expected in your major city. When the riots finally do break out, your sent into the streets with your fellow officers with no weapons, no bullets, all you have is a batton, a sheild, and maybe some peper spray. You of course have your protective gear and all that as well. Now you have a 20 something college drop out screaming in your face saying how your perpetuating the man, and all you want to do is go home and sleep and be with your wife and children. These people, the majority of whom dont live in your city, are ripping appart the place where you live, and work. Their actions completely invalidate the job you have been doing for years because you cant provide the protection the citizens diserve. Then some one sets something or another on fire, and you get hit in the face plate with a rock thrown by some one who is protesting the WTO when they have never had a job in their life. The tear gas is deployed and your face burns because the department has not been given enough money to buy desent gas masks. Shots have been heard and some one out in that crowd has a gun, you just hope you dont get shot so you can go home. The riot still is not dispersing so your ordered in, people screaming incorently infront of you, calling you names and saying you did things you never even thought about doing. You lash out with your batton at some one who dident follow the first second and third warnings, and screamed a curse word at you, but god, all you want to do is go home.
Riots are inexcusable behavior used to try and force government to follow a policy the mob wishes to dictate. They wish the policy to be followed weither or not they have all the information and weither or not its posible to complete, all they know is they want it, or they are burning something.
The police use rather humain methods to put down riots, I think people can start complaining then the army starts breaking up riots and people are fired on at a regular basis.