Dear police: The people are watching

It's not often that you see someone shot to death before your eyes – and even rarer that you have the presence of mind to record it. Martin Baron isn't really sure why he pulled out his cellphone early Saturday morning. But he did, and now the city of Toronto is rightly demanding answers.

Mr. Baron, 47, was walking home with his wife and 19-year-old son when they saw armed police officers approach an empty streetcar in their west-end Toronto neighbourhood. In the video, their guns are drawn. There is a lone figure in the streetcar. Someone tells him to drop the knife. One officer opens fire. Nine shots ring out in rapid succession, then someone fires a taser for good measure.

"I saw them perform CPR through the window," Mr. Baron told me Monday. "And my reaction was, why would they do that? What's left of the guy?"

By the time the suspect arrived at the hospital, he was well and truly dead. His only weapon was the knife.

Mr. Baron's video instantly went viral. Thousands of people watched it online and on television. On Monday morning, Toronto Police Chief Bill Blair responded to the widespread outrage by announcing that he will hold his own chief's investigation into the death. He, too, had viewed the video, and said he was aware of the serious concerns among the public.

"It's not my role to judge police," Mr. Baron told me. "But the whole situation is extremely puzzling."

To say the least. According to witnesses, the young man, 18-year-old Sammy Yatim, became agitated and pulled out a knife on the streetcar. The driver stopped and opened all the doors, and the passengers rushed out. By the time police arrived, the suspect was alone in the car. They seemed to have him cornered, but appeared to make little effort to reason with him, to calm him down, to use the taser first, to shoot to injure – any method short of lethal force. They could have left him alone until more help arrived. But they barely hesitated. It looks as if they shot to kill.

Mr. Baron's video doesn't tell the entire story, of course, and we haven't heard the police side. But without Mr. Baron's video, the police might not be on the hot seat today. What it shows is far more damning and immediate than a bunch of conflicting eyewitness accounts could ever be – and it makes a cover-up impossible. A citizen cellphone video was the only reason the truth about Robert Dziekanski's death ever came to light. He was the Polish man tasered by the RCMP at the Vancouver airport in 2007. His death was eventually ruled a homicide.

The ubiquity of surveillance has plenty of downsides. But the ubiquity of cellphone cameras makes every citizen a potential watchdog. That changes the balance of power between police and citizens – in favour of the citizens. Most police are good guys, but some are not, and never again will it be so easy for them to get away with incompetence, brutality and abuse of power. The people are watching. And they're putting what they see on YouTube.

Mr. Baron, who is trying to get back to his real job as an architect, said it feels peculiar to be an agent of citizen justice. He hasn't watched his own video more than a couple of times because the sound of the gunshots makes his skin crawl. "My kid is a tall skinny kid like that kid," he said. "It just hits too close to home."

Fifty-six per cent of us now have smartphones. They're turning out to be a powerful weapon for the public good. "The pressure to find an answer is red hot," said Mr. Baron. "If the video helps get to the truth, that's really all I could hope for."