National Association of Snivilian Oversight of Law EnfArcement:
Historically, in the US, criminal prosecution of officers has been rare for several reasons, including these:
C the highest standard of proof is required for criminal prosecutions; therefore, prosecutors may decide that a criminal allegation is not provable at the beyond a reasonable doubt level required.
C due to officer / community safety considerations and officer discretion, police are given special protections and special justifications for actions which might otherwise be alleged to be criminal.
The point to be made is that while the penal law applies to police as it does to everyone else, proving beyond a reasonable doubt that an officer committed a criminal act of misconduct is complicated, difficult, and infrequent.