A Williams Lake, B.C., teen who claims she was punched in the face by an RCMP officer during a September 2011 arrest is expected to testify at his trial today.

Jamie Haller was 17 at the time of the incident.

The First Nations teen claimed she was fleeing a gang when police were called to respond. She was arrested, handcuffed and put in the back of a police cruiser.

Haller alleges it was at that time she was punched repeatedly in the face by Const. Andy Yung, who is facing a charge of assault.

“This whole issue in the trial is what happens when a First Nations person in the Interior of this province calls 911 for help,” said Joshua Patterson, executive director of the B.C. Civil Liberties Association.

Patterson says there are systemic issues around how RCMP deal with native people.

"This isn't just something we've seen happen in Williams Lake. We've seen incidents of police violence against aboriginal people right across the north. There have been several other cases of concern."

The incident was investigated by Abbotsford police, who recommended to the Crown that Yung be charged.

With files from the CBC's Marissa Harvey