Final answer:
Police officers are permitted to use deadly force to protect an innocent bystander from imminent grave danger, but it is considered a last resort after assessing the risks involved.
Step-by-step explanation:
An officer may use deadly force if he or she believes an innocent bystander is in grave danger of suffering great bodily harm or death. This principle is part of use-of-force policies and laws that police officers must follow to ensure the safety of the public.
The use of deadly force is considered a last resort and officers are trained to assess the risk to innocent bystanders before acting. In situations where there is an imminent threat of death or serious injury to others, officers may determine that using deadly force is necessary to prevent the threat from materializing.