TRAINING is so important. Especially when - as a profession - LEO are so under the microscope/gun at the same time. ANYONE can have a bad day/slip up and let someone "have it" verbally or even physically if buttons are pushed.
Its never condoned of course, but, its like medical malpractice. Everyone knows a doctor is a human being, and that humans err. BUT, if they DO make a mistake, they do NOT "get away with it". They are raked over the coals, and drawn and quartered in court. (Drawn and Courted?)
In some professions, you are not allowed to make a mistake, ever, period. This is of course unrealistic, and yet, is the reality of it.
My feeling is that people who choose such a profession MUST know where the bar is, and how high it is.
To that end, there are people who check on the activity around that bar, and see if anyone tried to sneak under it. These people who pass the bar are called lawyers. They get money from the ones who go under the bar, and give 60% of it to the people who set the bar the guy went under.