HALIFAX -- New details have emerged after Halifax Regional Police responded to a cellphone video showing the use of force, including a stun gun, during an arrest of a man after a traffic stop.

A video posted on social media Wednesday night appears to show the moment a stun gun is used by Halifax police during an arrest on Quinpool Road late Wednesday afternoon.

Police say it began with a traffic collision when two officers observed a vehicle hitting two others while changing lanes. They gave the driver a ticket.

"Once the summary offence ticket had been issued, the driver took exception to that, and an altercation occurred between the driver and our officers that were on scene," said Halifax Regional Police spokesperson Const. John MacLeod.

At that point, police say two additional officers were called in.

They say that's when the driver assaulted one of the officers -- although the department won't say how.

A surveillance video obtained by CTV News appears to show the moment when police issued the ticket and what happened next.

A 62-year-old man now faces charges of assaulting a peace officer, obstructing and resisting arrest, and causing a disturbance.

Police say no injuries have been reported.  The driver is due to appear in court at a later date.

Law professor Wayne MacKay says judging a proper use of force requires looking beyond the one-minute video.

"Was it reasonable in order to arrest him, to use the stun gun?" says MacKay, a professor emeritus at Dalhousie University's Schulich School of Law. "In order to answer the question of whether it was reasonable force, and necessary force, which is kind of the Criminal Code standard, you need to look at the whole picture, and what we have is one segment of that."

The province's updated guidelines for stun gun use by police state the weapons will only be used if an officer believes the subject's behaviour includes "aggressive or violent resistance" or "presents an active threat ... that may cause bodily harm or serious injury" to anyone.

Halifax Regional Police say all incidents involving force -- including the use of stun guns -- are reviewed internally.

Halifax social worker Robert Wright was among those calling for an apology from police for years of illegal street checks targeting African Nova Scotians. That apology came from Halifax police last Friday.

This arrest of a person of colour is a different situation, he says, but it comes at a sensitive time.

"The timing is unfortunate," said Wright. "Do the police have the confidence of the people, so much so, that people, and in particular black people, are going to feel comfortable waiting until the investigation?"

Police say information from any internal review is not generally made public.

CTV News contacted the province's Justice Department and a department spokesperson only said: "police agencies are required to have operational policies and procedures in place to guide their use of stun guns."

Halifax Regional Police would not speak on Thursday to its specific rules for the use of stun guns.