Research the correlation between psychiatric drugs and violence. Correlation does not equal causation, of course.
Think about this. There are no causes of illegal violence, there are only reasons for illegal violence. Psychiatrist Thomas Szasz manifested this thought in my mind through his writings. If you think about it for a significant period of time you will eventually realize that this is True.
Drugs can not cause illegal violence any more than demon possession causes illegal violence.
However, coercive psychiatry is a dehumanizing force. Even non-coercive psychiatry can be dehumanizing when it sends implicit and explicit messages that people are not responsible for their own behavior - that individuals are not responsible for their own thoughts and behaviors. We have control over our behaviors. We have a great deal of control over our thoughts.
My theory is that there is a significant correlation between psychiatric drugs and violence because the implicit and explicit messages that psychiatry spreads regarding personal responsibility increase some individuals reasons for engaging in illegal violence, and decreases some individuals motivations and reasons for not engaging in illegal violence.
Illegal violence should not happen. However, perhaps it is at least partially an unintended consequence resulting from dehumanizing aspects of psychiatry.
It seems to me that the dehumanizing aspects could largely be mitigated if nonconsensual psychiatry and the insanity defense are outlawed and banned.
Do you have a better theory?