Well, I'd say I can't answer that question authoritatively since its almost by definition context-dependent, in addition to asking the practical question of why

Well, I'd say I can't answer that question authoritatively since its almost by definition context-dependent, in addition to asking the practical question of why/how a police force is raised/employed and depends a bit on a subjective point of view. But empirically, i'd observe a couple of things in the Australian context: a) Assault may be a continuum, with stabbings/shootings on one end, to the point where, as I said, almost no one reasonably believes themselves to be potentially shot/stabbed. (almost no one reasonably believes they'll be assaulted, either). b) When people are assaulted or violently attacked, its almost infinitely more likely to be by someone intimately connected with them in their domestic or everyday environment, or in the context of drugs/alcohol. In that context, body armour appears to be to most people equally silly. c) By far most police's time would be dealing with other matters apart from primarily preventing assault: case investigation and handling, property and vehicular theft, burglary, drug related offenses, traffic (including crashes, random drug testing, etc), crowd and pedestrian control (which COULD be stretched into preventing assault in context), suburban and domestic disturbances (which again, COULD be stretched into preventing assault in context). However, even in those cases where it could be stretched into preventing assault, the notion of appropriate use of body armour (or being exposed to stabbings or shootings in such a context) would be seen as relatively absurd.