M. Quentin Williams can sum up the shooting of Walter Scott in a single, eloquent sentence:

“Everybody did everything wrong,” he says.

Scott shouldn’t have run away in the middle of a traffic stop, and North Charleston Patrolman Michael Slager shouldn’t have chased him, seeing as Scott was not armed or considered dangerous. Slager had his car and his driver’s license, Williams points out, so the guy was going to turn up.

And of course he shouldn’t have shot Scott.

Williams is in a unique position to make that analysis. The New York attorney, one-time Lowcountry resident and former FBI agent is author of “A Survival Guide: How Not to get Killed by the Police, Part I.”

In the guide, Williams offers some common-sense advice along with several tricks of the trade to help people get through encounters with the police. The title, which admittedly sounds a little over-the-top, is a nod to the exact question Williams has gotten from folks many times over the years.

As a former lawman, and a person who has been detained and arrested more than he’d prefer, Williams has learned a thing or two about these situations, including the most important thing:

“This is just about getting people home,” Williams says.

Today, Williams has been invited by Sen. Marlon Kimpson to testify before a S.C. Senate committee studying the effectiveness of police body cameras. Lawmakers would be wise to listen up.

Because Williams knows what he’s talking about.

Williams has been on both sides of the badge — sometimes at the same time.

In the guide, he relates a 1994 incident when he was walking down the street in Newport, R.I., and was stopped by local police, told to put his hands behind his back and lean on the patrol car.

Now, Williams would have been within his rights to get indignant. After all, they nabbed him because they thought he might have been the guy, who earlier in the day, had stuck a 9 mm in some man’s face and said, “What you gonna do now, white boy?”

Not only was Williams not in Newport at the time of the incident, he was on duty as an FBI agent. But even after he calmly asked why he was being detained, and alerted the officers to the location of his gun and badge, they still kept him 90 minutes.

That’s how cautious police are. Williams knew that, and acted accordingly.

Williams will tell you that 99.99 percent of police officers are just trying to serve and protect. But their No. 1 priority is getting home to their families at night, so they are not going to take any unnecessary risks with their lives.

For that reason, Williams says, you don’t make wise cracks, you show respect — and you show your hands. If an officer asks to see your registration, tell them it’s in your glove box and ask permission to get it.

Sudden moves, you see, are not a good idea.

“How Not to get Killed by the Police” is full of useful information, much of which people would not even consider on their own.

Ultimately, it is a lesson better learned from Williams than the hard way.

Today, Williams will tell lawmakers that he has yet to hear a good argument against police body cameras.

“If you want to gain trust for a department, you have to have a level of transparency,” he says.

Sure there are issues of privacy to be worked out in regards to body cameras, Williams says, but those can be dealt with. The point is to stop all these incidents that have blown the world up and pitted communities against police forces.

Fact is, body cameras protect police officers who do their jobs from unfounded accusations, and they protect the public in similar fashion.

The Senate would do well to heed Williams’ advice. As state Rep. Wendell Gilliard says, the time for study has passed. Body cameras may not be the silver bullet to all our problems, but studies show they save lives — and cut down on controversy.

Now, the best way to avoid all these troubles is not to get arrested. But if you are stopped, it would certainly help if you’ve read “How Not to get Killed by the Police,” which you can get for free at survivalguideseries.com.

Williams gives the guide away because he doesn’t want anyone to not have access to the information. A life is worth far more than the guide’s $10 suggested retail price. And a life is also worth more than the cost of body cameras.

Until police have them, download “How Not to get Killed by the Police.” The guide not only has the rare quality of being both informative and interesting, it might just save your life.

Reach Brian Hicks at bhicks@postandcourier.com.