It's as if there aren't two people involved in a given incident. Cops realize there are cases of "mutual combat" where both people have some fault. Same with divorce cases....both can be at fault. When there are two persons involved, PERSONAL responsibility means two persons could potentially have some fault. The fault of one does not somehow magically erase the faults of the other. Seems like common sense to me. :idunno:
In domestic violence cases rarely do both parties go to jail unless there's visual proof or collaborating testimony from eyewitnesses that both were combative. Usually there is a victim and an aggressor. The aggressor goes to jail, doesn't pass "Go" and needs more than $200 to bail out.