In the discussion of discretion, a case came to mind from about six months ago that involved a police officer shooting a perpetrator of a domestic dispute gone bad and included the two police officers having to try and restrain the man but failing to do so. The fact that the officer shot the man in the chest multiple times caused many to question his discretion of the situation.
http://www.kcrg.com/news/local/59182472.html
This is the a follow up article that expalins a bit more.
I remember this case when it happened, and my teacher from a previous class was a former detective and said that the news left out a lot of information that was crucial to how people felt and looked at the case. The police officers showed up, the wife and husband were fighting, the husband was drunk or in a rage, I can't remember. The two officers split the couple up while they were still fighting with each other. The officer with the husband was overwhelmed by him and the husband started choking the officer. The officer with the wife turned around and shot a taser gun at the man; it had no effect. Then the officer went up to the husband and put the taser gun against him, still no effect, then he shot pepper spray, nothing. The officer on the ground was getting his eye gouged out and almost lost his sight in that eye later on in the hospital. The officer on the ground feared for his life so he shot twice, officers are trained to shoot twice so it's not questioned as an accident; if he shot once they would think it was an accident, like he didn't mean to shoot the gun. Shooting twice means, I meant to do this because I thought my life was in danger. People always like to point the finger at cops when victims were killed by them. We want police there to protect us and are upset when they aren't there. Then when they finally do their job to protect themselves, we say they could have done better and try to wrongfully convict them. We can never jump to conclusions before we see all the facts.