BOB: From WNYC is New York, this is On the Media. Brooke Gladstone is on assignment this week. I’m Bob Garfield.

SOUND OF DEMONSTRATION

BOB: On the streets of New York City Wednesday, and around the nation, anger coalesced into loud protest as yet one more grand jury declined to indict a white policeman who had killed an unarmed black suspect.

This time the officially non-crime-victim was Eric Garner, who was being arrested July 17 in Staten Island, New York -- for allegedly peddling loose cigarettes -- when Officer Daniel Pantaleo disabled him with a departmentally banned choke hold.

ERIC GARNER VIDEO - "I can't breathe"

BOB: “I can’t breathe. I can’t breathe,” Garner pled, before breathing his last beneath a massive pile of New York’s finest. And those facts are undisputed, because -- unlike the murky final moments before the shooting death of Michael Brown in Ferguson, Mo., three weeks later -- we know exactly what transpired in Staten Island. The entire deadly episode was video recorded by a bystander with a camera phone.

WITNESS TAPE:  Once again, police beating up on people, [Cop: back up, get on that steps]  

BOB: How unlike the fog of Ferguson, where Officer Darren Wilson and eyewitnesses offered conflicting accounts, and grand jurors found the evidence inconclusive. In that case there was an actual smoking gun, but no smoking-gun video. In Eric Garner’s death, ruled a homicide by the city’s medical examiner, the whole world has been an eyewitness. Much as in November we were able to witness the shooting death by a Cleveland cop of African-American 12-year-old Tamir Rice, who was playing with a toy gun. And in September the shooting by South Carolina State Trooper Sean Groubert of an unarmed black man at a gas pump. Dashboard-cam video captured Groubert demanding Levar Jones’ driver’s license, and then, when Jones reached into his SUV for his wallet, opening fire.

TAPE: SHOOTING CLIP: GROUBERT “why did you shoot me?”

That video had rapid impact. Within three weeks, the trooper was dismissed and charged with felony assault. Hence calls for universal deployment of body-mounted cameras for on-duty police to record every official interaction. Here was President Obama on Monday announcing a plan to equip police departments with the technology.

OBAMA: “I'm gonna be proposing some new community policing initiatives that will significantly expand funding and training for local law enforcement, including up to 50,000 additional body-worn cameras for law enforcement agencies.”

And, as we shall see shortly, the evidence of their usefulness is compelling. But obviously not a panacea. Much of the incredulity and rage in Wednesday’s protests stemmed from the inexplicable insufficiency of clear video evidence in holding a cop accountable for deadly force.

TAPE: CROWD CHANTING "I CAN'T BREATHE"

The demonstrators chanted those infamous last words because they’d heard them with their own ears. Here’s one New York protester speaking to WNYC reporter.

PROTESTER: "It just makes no sense that they would turn around and say no indictment. even though with Mike Brown we were pissed, there was some question there and people had a right to have questions. But this you have the full video. So how can you not tell that this was wrong?"

Ah, wrong-ness. This is a matter that the highest resolution camera cannot resolve.  Officer Pantaleo testified that he knew he was being recorded while arresting Eric Garner. The late Eric Garner. The policeman wasn’t bothered. he said, because he knew he was performing his duties properly. To others, many of them marching the streets Wednesday, his lack of worry suggests something else:  a sense of impunity so deep that damning videos are just damn useless. Michael D. White is author of the study, "Police Officer Body Worn Cameras: Assessing the Evidence" In the study, commissioned by the US Department of Justice, he reviewed and analyzed the findings of several empirical studies on the use of body mounted cameras by police.

WHITE: There are 3 studies I reviewed in the DOJ reporter. The study that's gotten the most attention comes from Rialto, CA. What that study documented was when the officers in that police department began wearing body-worn cameras there were sizeable reductions in two important outcomes. One is officer use of force and the second is citizen complaints against officers. And the reductions I'm talking about are in the neighborhood of 90 percent for citizen complaints and about 60 percent for use of force. Those are alarming declines in those two important outcomes. The implication with those reductions is that it's a result of this civilizing effect. That is, officers are using less force and citizens are filing fewer complaints. Because the cameras are somehow changing the behavior of the two participants. And what's interesting is. The other two studies that looked at this were with the Phoenix police department and with the Mesa, Arizona police department. In both of those studies the researchers who conducted those studies found similar reductions in those two important outcomes. Not as large. But when you have three studies that are documenting consistently the same important finding, I think it's really intriguing.

BOB: One of the things you've learned in the study is the opportunity that body cameras provide to examine not just the final moments before something bad happens. But everything that has led up to it. In other words, the whole encounter from beginning to end.

WHITE: For a long time, police departments - when they reviewed police officer behavior during a critical incident - an officer involved shooting, they look at the time immediately preceding the use of force and at that time was there an imminent threat of loss of life or serious injury. Scholars have called that the split second syndrome. And what that does, is when you focus on that immediate time preceding the use of force you ignore everything that happened before that. The review any critical incident should look at the totally of decisions that were made by the officer from the moment he or she found out about the call. When you do that, I think that presents an opportunity to shed this split second syndrome. And to look more holistically at a police/citizen encounter.

BOB: Kind of like the black box data after an air crash.

WHITE: Yes, you know can look at the daily decisions and learn from that. Were there decisions the officer made early on that essentially painted that officer into a corner and pretty much guaranteed that there was going to be some use of force. This is has been something that's been discussed in great detail in teh wake of the Ferguson incident. Because there was no body worn camera and therefore we really don't know what happened during the encounter.

BOB: So if we had only that evidence to base policy decisions on. You'd go 'well, give every cop a body camera and also take every opportunity to report these encounters between police and citizens, but there is also this other questions. The privacy question. And that's a little more troubling. Tell me.

WHITE: The privacy issue is concerning in a number of ways. Legal scholars will tell you you have an expectation of privacy in certain places. Certainly in your home or your apartment and other places as well. Police officers wearing body cameras represent a potential threat to that. But there are also issues with sensitive or vulnerable citizens. You know, a police officer is conducting an interview of a child. Or conducting an interview of a sexual assault victim, or speaking with a confidential informant. Or there could be religious sensitivities that are coming into play. So I think departments need to be very informed what the state and local laws are. Because there is variation in state law with regard to citizen privacy. There are still some states that have a 2 party consent law where a police officer has to notify immediately that the encounter is being recorded.

BOB: Now beyond conduct and privacy issues -- there's a third pretty big element of all this and that is cost. The affordability not just of equipping officers but dealing with the vast troves of recorded material that are the product of switched on body cameras.

WHITE: It's actually relatively easy to purchase the hardware, the cameras, and put those on officers and send them out on the street. The difficult part now is to successfully manage that body worn camera programs. These cameras produce just a tremendous amount of data that has to be stored. And it has to be stored securely because the video from an encounter could be evidence in a criminal trial. Could be evidence in a civil lawsuit. Certainly it might evidentiary value to assist in complaint resolution. All sorts of things. The management of that data on the back end is significant both financially and in terms of manpower and resources. Each time there is a request for video someone in the police department has to sit down and observe that video to make sure that nothing is in the video that has to be redacted before the video can actually be released. The fact of the matter is in fact public video and it can be requests thru a FOIA request so the department does have to release and how are they going to manage that if vast amounts of data are being requested.

BOB: And finally there's the question: Considering the costs and the considering the privacy issues -- but notwithstanding the apparent benefits that you were able to glean from your study, is this going to be a universally adopted technology and will it happen soon?

WHITE: This technology is not going anywhere. I think police departments have been telling their officers for a while now that when they're on the street that they should assume that they're being recorded by someone or something thing. Whether it's a CCTV at a convenience store or a citizen with a cell phone. As time passes, police will embrace it. It doesn't take much for the reluctance in a police department to dissipate all it takes is one or two examples of an officers being exonerated of a citizen complaint before word begins to spread that 'hey, this isn't big brother trying to get me this is a tool that's going to help with our interactions with citizens and it's going to help us to better manage our police departments.

BOB: Mike, thank you so much.

WHITE: My pleasure.

BOB: Michael D. White is professor at Arizona State University's school of criminology and criminal justice. And author the Department of Justice study - Police Officer, Body Worn Cameras: Assessing the Evidence.