The only legitimate and Constitutional requirement of a police officer is to enforce the law.
Hahahahahahahahahahahahahahahahaha, that was a good one, whew my sides are aching, thanks I needed that!
Anywho, where are you getting your information? however since you want to focus on constitutional requirements, here ya go:
Law Enforcement and the United States Constitution – Utah ...
www.utahstatetrooper.com/law-enforcement-and-the-united-states-constitution
Apr 30, 2013 · Law Enforcement and the United States Constitution. The duties of police officers center on enforcing laws, detecting and deterring criminal activity, arresting suspects, and maintaining the public’s safety, peace and order. To accomplish these duties and responsibilities officers are given significant power and authority.