What was it someone once said.. "We train our soldiers to kill. Then we give them strict Rules of Engagement, and trust them not to kill potential enemy combatants in the worst of situations when their lives are in danger. The police are trained to protect and serve, but are cheerfully allowed to shoot down their own citizens because it's potentially too dangerous to give them a chance and there's a risk they might get harmed themselves."
Yes, that might be paraphrasing it a touch, but it was an interesting point.