Ensign Davis was in an establishment that served alcohol, and while she had consumed alcohol it was determined that she was not legally intoxicated. Another patron of the establishment physically assaulted Ensign Davis causing her to defend herself, which is legal. An off-duty, and not in uniform, New Jersey police officer then approached Ensign Davis from behind, failed to identify himself nor make any statement before putting hands on Ensign Davis causing her, assumably, to believe she was being assaulted by another patron, so she struck him, also in self defense. While striking the off-duty officer as well as the other patron might be investigated, Ensign Davis, being the victim, would probably never be charged for any crime by civilian, nor military, authorities.
One of the members of Davis' disciplinary review board is a Warrant Officer One, Davis is an Ensign and therefore outranks him. UCMJ regulations state that someone cannot sit in judgment over a superior officer.