But has the would-be proof from a phone or security camera muddied the waters in new ways?
Grant Fredericks, a former Vancouver, British Columbia, police officer who operates his own business, Forensic Video Analysis, says digital technology can be deceiving. Fredericks, who has testified as an expert on the subject and has trained FBI agents, said both defense and prosecution lawyers can discount how misleading a video can be.
"There's an old adage, the video is a silent witness," he said. "That's an extremely dangerous idea today with digital video. Digital video is not what people think it is. In most cases, it's an altered and compressed medium."
Video technology in most cases does not record enough images to exactly replicate reality, Fredericks said. Transferring video through e-mail or YouTube further compresses video.
"The appearance of motion and force is distorted," he said.
Fredericks reviewed video of Josey's actions and noted several missing images in the video, which would result in the key event occurring faster than it actually did.
In a frame-by-frame analysis, Fredericks tracked the bottle in the woman's hand, and said Josey's hand seemed to go for the bottle. He observed in an e-mail: "If the officer stated that he was reaching for an object in the woman's hand and mistakenly struck her when his attempt was to strike at the object, then the video may support that."
Try telling that to Mayor Nutter, who said he had watched the Josey video repeatedly. "It's beyond my comprehension as to how that is not at least simple assault," he said.
Or to Police Commissioner Charles H. Ramsey, who fired Josey partly based on what he saw in the video.
Defense attorney Evan Hughes won an acquittal on assault charges for community activist Askia Sabur last week after the jury saw video of officers repeatedly striking him.
"Often video can be the best evidence available," he said after the Josey verdict. "Invariably, whoever doesn't like the video will claim the video doesn't capture everything or what happened before the video started."
Hughes also represented a defendant in the case in which a news helicopter captured video of police officers beating the occupants of a car who later were charged with a shooting. The jury acquitted the defendants, he said, even with a police eyewitness to the shooting, on the argument that the charges were manufactured to justify the beating.
He discounted Frederick's caveats on digital technology.
"The iPhone shoots in HD," he said. "The very nature of video is dispassionate and unbiased. Just because a video does not show an incident from start to stop does not mean it's not valuable."
Video evidence now carries more weight than eyewitness testimony and other forensic evidence for jurors, Hughes said.
"If you have a video of what looks like someone getting punched in the face, and there are medical records showing they did, in fact, get punched in the face, whatever distortion is on the video doesn't really matter," he said.
The tale of the tape can cut both ways. Defense lawyers use videos to prove alibis or undercut witnesses.
"Historically, I think video has been a tool of the prosecution," Hughes said. "However, in the past 10 years, we have seen defense attorneys use it more and more, with great success."
American Civil Liberties Union senior staff lawyer Mary Catherine Roper said video had leveled the playing field when citizens accuse officers.
She said complaints that officers interfered with citizens photographing them had declined since Ramsey ordered officers not to object.
"It's the most effective tool against police brutality we've ever had, but it's not always going to win the day," Roper said.
She noted that in the helicopter video case, a grand jury declined to indict the officers.
"On the one hand, it prevents the 'I never touched her' argument, but just like any evidence, you're going to argue over what it shows," she said. "It has completely changed the level of accountability that we have for police officers.
"People understand that not everything is genuine, not everything is what it appears to be," Roper said. "That doesn't mean it's not really important that we have this tool."
Contact Amy S. Rosenberg at 215-854-2681 or firstname.lastname@example.org. Follow on twitter @amysrosenberg.