The complexity of storing video evidence is enormous. Some videos in capital crime cases must be kept indefinitely, others, only as long as a criminal case takes to run its course, Tuttle said.
A relatively simple DUI arrest, however, could go on for months or years, depending on appeals, Tuttle added.
Gartner analyst Jeff Vining said the amount of video data that body cameras will create as their adoption escalates is "enormous."
The city of Los Angeles, for example, had initially planned to deploy 200 to 300 of Taser's body cameras for various shifts and locations. Then Mayor Eric Garcetti announced a plan to equip all 7,000 officers with body cameras.
"That caught everyone by surprise," Vining said.
L.A. police officers began strapping Taser's palm-sized cameras on Monday.
"You've got the [Los Angeles police] IT department cringing. Do you know what that entails?" Vining said. "And, of course, they don't."
Politics ahead of policy
Vining said the problem with the recent push for police body cameras is that the political pressure spurring their adoption has gotten ahead of evidentiary procedures and the storage technology required to support them.
The fatal shooting of Brown, an 18-year-old black man, by a white police officer in Ferguson, Mo. in August 2014 marked a turning point. After the Ferguson shooting, trials of Taser's body cameras by police departments in major U.S. cities tripled; Taser's stock price also has more than doubled since that time.
"What [Ferguson] did for us was put a tremendous spotlight of the body camera's availability in public's knowledge," Tuttle said.
"One of the biggest things we have noticed is that our request for trial units have gone up over 75% since the Ferguson incident," said VieVu's Ward.
This week, for example, county commissioners in San Antonio approved funds for additional body cameras for sheriff's deputies. The funds were approved just hours after the release of a video that showed two deputies fatally shot a Hispanic man who appeared to have his hands up in the air.
Although the push for more body cameras is growing, several states still have laws requiring suspects to consent to being videotaped, Vining said.
And there are the associated costs, which have drawn far less attention.
"There's the enormous storage and data management cost, which is daunting," Vining added. "A records management system is a police department's Bible. If you're going to create video content, it has to be accessible to the records management system."
Just as with any physical evidence, video footage must be tracked with a chain of custody, and there are digital rights management issues that determine who can and cannot access police video. The Criminal Justice Information Services Division (CJIS) of the Federal Bureau of Investigation (FBI) governs policies for securely storing video content.
VieVu pitches its video service as more compliant with CJIS policies because it's based on the Windows Azure Government cloud, which uses more advanced security and requires government audits.
What kind of cameras, and how many?
Safariland's VieVu has distributed body cameras to some 4,000 police agencies, according to Tuttle. Scottsdale-based Taser said it's shipped 52,700 body cameras to 3,500 police departments.
Taser sells two types of cameras: The Axon Flex camera ($599) is a micro-camera that can attach to a pair of sun glasses or the visor of a police officer's cap, so as an officer's head turns, it captures what he or she sees. The camera attaches by cable to a mini-DVR that's also on the officer's body.
The Axon Body camera ($399) is a larger camera that attaches to an officer's shirt or vest and offers a wider-angle view. Both Axon cameras have a single button that a police officer can tap twice to activate them.
In default mode, the Axon cameras record at 480p resolution and can store about 8GB of content.
"Most officers record 60 to 90 minutes of video per day," Ward said. That's because officers only activate their body cameras when they believe they need to, such as during a traffic stop or when confronting a suspected criminal.
Both Taser and VieVu sell docking stations for the cameras that automatically upload video to the cloud, while also recharging the devices.
Once uploaded to either Taser or VieVu's cloud video evidence management services, police can maintain a chain of custody of those videos, search them using metadata and set retention policies for each one.
Pricing for Taser's Evidence.com cloud storage service ranges from $15 to $79 per month, per user. Taser's Officer Safety Plan, which automatically replaces old cameras every 2.5 years, costs $99 per officer per month.
VieVu sells its VERIPATROL cloud service as a bundle priced at $55 per month per officer. After purchasing an LE3 camera for $199, the VieVu Solution includes the VERIPATROL secure file management software and 60GB of storage, which can be increased for 12.5 cents per gigabyte per month). An onsite storage software bundle sells for $25 per officer per month.
The cost is worth the results
While the cost for video cloud storage services may be high, studies have shown the use of police body cameras has reduced citizen complains and officer use-of-force incidents.
In 2013, a year-long study by Cambridge University of the Rialto, Calif. Police Department's use of Axon Flex cameras showed use-of-force incidents dropped by 59%, and citizen complains dropped by 87.5%. The study encompassed more than 50,000 hours of police-public interactions.
"These results carry significant implications for the future of the law enforcement profession," Rialto Police Chief Tony Farrar said in a statement at the time of the study's release.
Farrar was the principle investigator who led the study as part of his graduate degree thesis at Cambridge University.
According to Vievu, the Oakland Police Department was able to reduce use-of-force incidents by 73.8% over the five years since it deployed 619 body cameras.
While the cost and data management headaches may be significant, Birmingham's Brewer said they're all outweighed by the payback: an increase in public trust and fast incident resolution.
Body cameras not only force officers to be more careful about how they execute their duties, but once a citizen is informed they're being recorded, their behavior becomes more civil, too, he said.
Noting the recent drop in use-of-force incidents -- and citizen complaints -- Brewer said body cameras and the accompanying video storage easily achieve a return on investment.
"If it stops one or two lawsuits, it's paid for itself," he said.