(PORTLAND, OR) -- Assault charges were dismissed Thursday against a school board member accused of using pepper spray on a teen-ager she thought was a prostitute.

Prosecutor Dan Reynolds didn't say why he dropped the charges against Parkrose School Board member Jennifer Young, who has been crusading against prostitution in her neighborhood for the past four years.

A 15-year-old girl claimed that Young sprayed her on June 6 after photographing her and following her to a grocery store, where she and her mother confronted Young in her car.

Young left Thursday's arraignment hearing without comment.

Her lawyer, Martin Reeves, said she saw the girl emerging from what she said was a known prostitute's hotel room, took her picture and prepared to leave the grocery store parking lot. Reeves said the girl, joined by her mother, blocked Young's car and began kicking the door. Young sprayed the girl in the face, he said.

``My client was fearing for her safety,'' Reeves said. ``She didn't go out to harm anyone.''

Reeves said he didn't know why the charges were dropped.

School board members have urged Young to resign, saying her neighborhood-improvement efforts have often turned into angry campaigns to discredit her opponents.

``She's just a very difficult person to communicate with,'' said Karen Rutledge, school board chairwoman.

Last year, Multnomah County Sheriff Dan Noelle revoked a concealed weapons permit Young had obtained in 1997 for a handgun, saying in a certified letter that Young ``continued to be a vigilante.''

Reeves said Young has no plans to resign from the board.