The Fifth Amendment prevents compelling a police officer facing criminal charges to turn over to prosecutors a flashlight he allegedly used to beat people during an off-duty street fight, a state appeals court held on Wednesday.

The Appellate Division, in State v. Kelsey, A-4850-10, upheld a Mercer County judge who found that ordering Patrolman Mylon Kelsey to turn over the flashlight would be “comparable to having [d]efendant make the prosecution’s case against himself.”

Kelsey, a seven-year veteran of the Trenton Police Department, is facing aggravated assault and weapons charges in connection with the incident, a 12-person melee outside the TirNaNog bar in Trenton on Jan. 17, 2011.

The department’s Internal Affairs Division launched an investigation after the father of one of the people injured reported that off-duty Trenton police officers were involved. A witness said Kelsey struck several people on their heads with a flashlight. After obtaining a search warrant, investigating officers, found an empty flashlight box in Kelsey’s car.

Superior Court Judge Robert Billmeier granted the Morris County prosecutor’s request to compel Kelsey to turn over the flashlight but, on a motion for reconsideration, changed his mind, stating, “The act of actually turning over the flashlight is inherently incriminating.”

On appeal, the prosecutor cited a string of cases in which suspects have been required to provide items of forensic evidence, albeit potentially incriminating. They include urine samples relating to drug use, blood samples relevant to intoxication and genetic material in rape cases.

Appellate Division Judges Jose Fuentes, Ronald Graves and Jonathan Harris, said those rulings do not apply, since “none of the cases cited have compelled defendants to divulge the location of incriminating physical evidence, or otherwise incriminate themselves by the mere act of responding to the question itself.”

Fuentes quoted Chief Justice Joseph Weintraub in In re Addonizio, 53 N.J. 107 (1968), who said a defendant can’t be “subpoenaed to produce the gun or the loot, no matter how probable the cause, for the Fifth protects the individual from coercion upon him to come forward with anything that can incriminate him.”

Neither Kelsey’s attorney, Scott Krasny, of Ewing’s Furlong & Krasny, nor Assistant Mercer County Prosecutor Stephanie Katz returned telephone calls seeking comment.