A New Brunswick Mountie who made headlines for smoking medical marijuana while in uniform has pleaded not guilty to three charges.

Cpl. Ron Francis is charged with two counts of assaulting a police officer and one count of resisting arrest, stemming from an alleged confrontation with fellow RCMP officers and Fredericton police officers who arrested him on Dec. 6.

Francis, who was previously found fit to stand trial following a 30-day psychiatric assessment, did not appear in Fredericton provincial court on Tuesday. Defence lawyer T.J. Burke entered the pleas on his behalf.

A trial has been scheduled for Sept. 3. Three days have been set aside.

Burke told reporters outside the courtroom he plans to "call lots of witnesses and call lots of evidence and get right down to the bottom of why Mr. Francis is facing three charges."

Police maintain Francis was arrested by the officers because they were concerned about his well-being.

RCMP have said they had a form that allowed them to hold him under the Mental Health Act for 72 hours for fear he would hurt himself or someone else.

They asked the Fredericton Police Force for assistance, which led to the alleged altercation with Francis. Officials have said he had to be subdued by a stun gun.

Burke has previously questioned the RCMP's motives for seeking a psychiatric assessment of his client. He questioned whether the RCMP were trying to stop Francis from taking his case to the media again.

Francis, who has a prescription for medical grade marijuana to treat his work-induced post-traumatic stress disorder (PTSD), had publicly argued he should be able to smoke the drug in uniform.

The 21-year veteran of the RCMP was stripped of his uniform and placed on medical leave in November after smoking medical marijuana on video while wearing his red serge.

Francis remains free on conditions until his trial. He must not be in possession of a firearm, not use alcohol or non-prescription drugs, and not have contact with the alleged victims.