The Guam Lieutenant Governor Ray Tenorio, who is standing for re-election in November, is facing misdemeanour charges of official misconduct, reckless conduct and obstructing government function.
The Pacific Daily News reported the complaint had been filed against him by the attorney general's office in the Superior Court.
The investigation relates to a gun-grabbing incident at a 7 July event in Tumon.
In a statement, Mr Tenorio said he was confident that the courts will find him innocent and reaffirm that his actions were in the interest of public safety.
He said he would clear his name of what he called a politically motivated attack.
Mr Tenorio has said he saw a police officer at the event with what he regarded as an unsafe firearm.
The Lieutenant Governor said he lifted the firearm out of the officer's holster and returned it.
Charging documents state Mr Tenorio was red-faced and reeked of alcohol during the incident and grabbed, or attempted to grab, the officer's gun six times.