If someone see's harm being done to another innocent human being.
You should:
A. pretend like you don't see it.
B. intervene in some way.

It is a "right" given by God to self defense, and to use the force necessary to subdue the threat. The threat can be neutralized in seconds or maybe it takes several years, the onus is on the challenger.

It never gets boring, but I think the days of the passive Christian are near over.