Alycia Morehouse, a spokeswoman for the department, says Cpl. Ron Francis is undergoing a psychiatric assessment at the Restigouche Hospital Centre in northern New Brunswick after he was arrested last week.
Francis is due back in provincial court in Fredericton on Jan. 6.
An RCMP spokeswoman says the Mounties were concerned about Francis's well-being when they found him Friday on a street in downtown Fredericton.
Morehouse says the RCMP called Fredericton police for help because the city is not within RCMP jurisdiction.
She says Francis was hit with a stun gun at one point, but she couldn't offer further details, saying the matter is before the courts.
Francis attracted national attention last month when he spoke out against the RCMP's policy that says its officers can't smoke medicinal marijuana while in uniform.
He returned his red serge on orders from his superiors but accused the RCMP and the federal government of not doing enough to support officers with post-traumatic stress disorder.
The RCMP said its officers who are prescribed medicinal marijuana should not be in red serge or regular uniform while taking their medication as it would not portray the right message to the public.
The lawyer for Francis could not be reached for comment.
Note to readers: This is a corrected story. A previous version said Alicia Morehouse was a spokeswoman for the province's Public Safety Department.