Saying that video game violance causes real life vioance is like saying that the shooting of Fransis Ferdinand was the only cause of the start of World War 1.
It was a factor, like all things are a factor. On its own, nothing, but in the right situation it suddenly makes the situation deadly. Volo is right, someone who would kill because of a computer game is a loonie anyway, however, what if they didn't kill without the computer game? This is the real issue here, those in charge know that those with a firm grasp of reality arn't going to go on killing sprees, and frankly, the number of people who would, for the game *alone* is so small that it is almost worth not thinking about. However, it is combined factors that dont help.
Look at Soldier of fortune, you had a game over on killing US citizens, and yet, could massacer arabs at will, some people claimed this was because there was nothing in your mission that forbade killing arabs so it was okay for the game devs to allow this, but what kind of effect does it have when a game like this that (while it doesn't promote, but still *allows*) is realeased right after an incident like 9/11. Does it promote race hatred and an idea that 'arabs are scum and deserve to die' or is it somehow cathartic? It's all well and good saying that 'but people are intelligent' but actually they arn't, and if you were somone desperately trying to stop the spread of racial hatred in a time when your people are being patticually persicuted, does a game such as Soldier of Fortune, released at the wrong time do anything to help anyone? The only hope is that it does no harm. But on the other hand, games are entertainment, why should they even TRY to help anyone, if the game devs don't want to try and help people on some level through their medium then they have no reason to and all the goverment can do is try to stop them doing what they see as harm.
In this way, as with most laws, it's the actions of a few stupid people (in this case, devs who use 'touchy' material just because they can) who create restrictions to those who would use said touchy material in an actually productive way.
RANT OVER, BYE.