common sense and training, preplanning for situations...so one can act with greater speed and act correctly...statutes don’t always tell one what to do, and neither does case law.
statutes use the word reasonable but don’t go into detail what is reasonable..but then you knew that, that is a split second decision made by the cop on the street facing all kinds of situations that arebeyond the ability to be statutized
But self defense as a defense to manslaughter is dictated by statute