On April 4, North Charleston, S.C., police officer Michael Slager leveled his service weapon and fired eight shots at a fleeing, unarmed Walter Scott. Sometime in that span, some of Slager’s bullets struck Scott in the back — four times an autopsy later revealed — and the 50-year-old man collapsed and died.

How do we know this? Certainly not through the account Slager gave. He immediately began concocting a story, telling a dispatcher that Scott “grabbed my Taser,” implying that he was forced to shoot the man, and later saying through an attorney that he followed appropriate policies and procedures during the encounter.

No, we know what really transpired because Feidin Santana happened to be walking by. Santana turned on the video camera in his cellphone and captured the crucial moments that revealed the truth. Slager wasn’t threatened. There was no struggle for his Taser. He simply gunned Scott down.

And we might never have known had there not been that video.

Millions of people carry cellphones equipped with still and video cameras now, which means that those in authority who cross the line don’t get to simply sweep it under the rug. Whether they think of themselves as citizen journalists or just concerned citizens, they have a powerful tool at their disposal and should not be afraid to use it.

Of course, I’ve never been hauled into court for doing that very thing. Felicia Gibson was. In 2009, she began videotaping a traffic stop involving multiple Salisbury Police Department units in front of her home on West Fisher Street. Several people were standing outside watching, but apparently only Gibson — standing on her own front porch caught the attention of the late Officer Mark Hunter. After ordering her back into her house, Hunter chased the retreating Gibson inside, cuffed her and took her to jail.

Even more shocking, Rowan County District Court Judge Beth Dixon found Gibson guilty of resisting, obstructing or delaying an officer, ruling that Gibson interfered with Hunter’s ability to do his job. He was in the street, while she was on her porch. Was it the video camera that caused such grievous interference? He didn’t drag anyone else out of their homes. The city later paid Gibson a $25,000 settlement.

If someone had been taking video on Aug. 9, 2014, in Ferguson, Mo., we would have immediately known the truth about the shooting of 18-year-old Michael Brown by Officer Darren Wilson. Wilson said he and Brown struggled and he shot Brown in self-defense. Some witnesses said Brown had his hands up to surrender when he was shot. Wilson wasn’t indicted, and he was cleared in a federal civil rights investigation. A video would have made the would have made the investigations far easier, and it might have saved Ferguson from months of sometimes violent protests.

In the wake of the Ferguson case and others like it, there’s been an outcry for more police officers to be outfitted with body cameras. A bill filed this week in the N.C. General Assembly, however, would exempt those videos from public inspection, along with patrol car dash camera videos. N.C. Rep. Harry Warren of Rowan County, a co-sponsor, says making those videos part of the public record is “leaving law enforcement open for frivolous claims of police brutality.”

It seems having video evidence publicly available would have the opposite effect if the officer acted appropriately. And having them shielded from public scrutiny would do nothing to engender more confidence in police from communities that already have little.

It’s indisputable that publicly available video can further justice, as it has in the case of Slager and Scott. North Charleston Mayor Keith Summey told reporters “that as the result of that video and the bad decision made by our officer, he will be charged with murder.”

I’m not encouraging people to take to the streets looking for trouble with their cellphones. I’ll just quote the advice U.S. Rep. Jim Clyburn, of South Carolina, gave in an interview with MSNBC: “Keep the battery charged.”

Scott Jenkins is news editor of the Salisbury Post.