The use of the word 'violence' felt odd and inciting and disingenuous and very loaded in these contexts. I think the word the author is actually describing is 'force'. Police have the legal capacity to use
force, not violence. That's why we have a legal concept of deadly force, but not one for deadly violence.
Putting someone in handcuffs is not necessarily violent, but it involves using force to impose the will of the state on an individual.