50 states - 50 failures
"Every state in the US fails to comply with international standards on the lethal use of force by law enforcement officers, according to a report by Amnesty International USA, which also says 13 US states fall beneath even lower legal standards enshrined in US constitutional law and that nine states currently have no laws at all to deal with the issue."
furthermore:
" ... compared state statutes on law enforcements use of lethal force with international legislation, including the enshrinement of the right to life, as well as United Nations principles limiting lethal use of force to unavoidable instances in order to protect life after less extreme means have failed. Further UN guidelines state that officers should attempt to identify themselves and give warning of intent to use lethal force.
Amnesty found that in all 50 states and Washington DC, written statutes were too broad to fit these international standards, concluding: None of the laws establish the requirement that lethal force may only be used as a last resort with non-violent means and less harmful means to be tried first. The vast majority of laws do not require officers to give a warning of their intent to use firearms.
http://www.theguardian.com/us-news/2015/jun/18/us-states-police-use-of-force-standards-amnesty