I come from St. Louis where I received some Law Enforcement training and minored in Criminal Justice in college, I am by no means an expect and things may have changed since over time but I believe that the situation is left to the officers discretion when it comes to an armed suspect. A fleeing suspect will be very difficult to justify shooting, especially if their back is to the officer, I'd assume that'd be a case by case basis and certainly investigated heavily by Internal Affairs. The officer will have had to use ALL of his other means to subdue the suspect and to prevent the situation from escalating. This means going through the Law Enforcement Use of Force Continuum, you will have head to exhaust all other means of force (not literally).
Shooting always have negative impacts upon society, thus, they are certainly a last resort. Taking a live with deadly force is taking away someone's child, brother, lover, or friend. It will often have negative consequences associated with it and can sometimes escalate an already tense community situation into a more dangerous situation for the department and community at large. Gangs may retaliate against the department, the populace can become less cooperative, and the department can lose respect and authority within the community.
Violence should always be a last resort, especially when we have tazers and other non-lethal methods. I think many of you are lucky LCPD apparently has no Internal Affairs ;)
p.s. Shooting in the foot isn't legit either, lol. This ain't the wild west!