Relevance? Completely different country.
If you want more information on the legal use of deadly force in the United States, there is a great book called "Deadly Force - Understanding Your Right To Self Defense" by Massad Ayoob talking about this sort of thing. A lot of the case studies are about police officers.
Edit: This is a good article on the subject too https://www.theatlantic.com/ideas/archive/2018/09/amber-guyg...