With the ubiquitous presence of mobile phones and cameras throughout society we are all exposed to what others see and experience, whether carried on the 24-hour news cycle or posted on the internet. It is because of this we have now seen, many times, what can happen when a law enforcement officer exerts force upon a citizen; and what bad citizen behavior can look like to the officer. 

The number of guns sold in America ...

Law Enforcement - Citizen Violence