It seems inevitable that the bulk of the nation's police forces will one day be outfitted with body cams and dash cams.

The stocks of two of the leading companies producing some of this hardware, Digital Ally and Taser, attest to that. They are up substantially as police departments big and small are gobbling up such devices left and right. The authorities say the rush for the surveillance gear is being done in the name of transparency, to build a reviewable record of law enforcement's interactions with the public.

But when should that footage become public? Policies vary nationwide. Seattle police have created a YouTube page for their footage, but much of what is shown is blotched out to protect people's privacy. The Los Angeles Police Department said that the agency isn't likely to release its body camera footage, and officers there will get a chance to review footage before making an initial statement about what happened.

The latest fracas over whether a police video should become public is playing itself out in South Carolina, ahead of the upcoming trial of North Augusta Public Safety officer Justin Craven. A dash cam captured the white officer killing a black man—68-year-old Earnest Satterwhite Sr.—in the aftermath of Craven pulling over the man on suspicion of drunken driving.

Craven's attorney, Jack Swerling, said the video's release might soil "prospective jurors' opinions about the merits of the case both in favor or against a defendant." He said the video would be "repeatedly played and commented on" in social media and elsewhere. As such, he is asking a judge to keep the video under wraps.

The South Carolina Press Association said the video should be released promptly, as "the only people that haven’t seen it is the public."

Authorities say Craven followed Satterwhite to his house in Edgefield County. He approached the driver's side of the car and shot the man up to four times last year. The officer said that the man "grabbed my gun."

The episode was captured on Craven's dash cam. The officer is accused of discharging a firearm into an occupied vehicle, a charge that carries a maximum 10-year prison term. The City of North Augusta has agreed to pay the dead man's family $1.2 million to settle a wrongful-death suit. The video was viewed by lawyers in the case but nobody else.

The North Augusta Public Safety Department and the City of North Augusta have declined to release the tape so far, as have the 25-year-old officer's prosecutors.

Donnie Myers, the lead prosecutor in the case, said the time was not ripe for the video to become public. Doing so, he said, "would be harmful, unfairly prejudice the pre-trial opinions of potential jurors, prejudicial to the defendant, and not in the interest of justice."