Enlarge By Steve Cannon for USA TODAY Diop Kamau, a former police officer in California who is shown following a sheriff's car on patrol in Tallahaassee, Fla., on Sept. 9, has become a video chronicler of police activity. TALLAHASSEE  Diop Kamau's home in a leafy, gated community just north of town is not easy to find — for good reason. For more than two decades, the 52-year-old former Hawthorne, Calif., police officer has made a living embarrassing cops with a video camera. Stung by the rough treatment of his father during a 1987 traffic stop by another California department, Kamau turned to a second career recording police across the country in compromising — often abusive — encounters with the public. Some of the controversial videos made using hidden microphones and cameras found their way to network and cable television, exposing police to deserved criticism. Mostly, the videos helped launch a new generation of public accountability for local law enforcement. One of Kamau's most effective weapons is a battered 1968 Chevrolet Impala, wired with microphones and cameras, that Kamau, who is black,drives to test the racial profiling tendencies of local police on behalf of paying clients. "Frankly, there are a lot of people with badges and guns who don't like me very much," Kamau says, motioning to the network of surveillance cameras that protect his home from unwanted visitors. "I step on a lot of toes." Starting with the grainy images first broadcast by Kamau and other pioneer citizen watchdogs — notably the 1991 beating of Rodney King in Los Angeles, shot by a nearby resident— the public surveillance of cops has exploded to potentially include anyone with a cellphone. The videos are so ubiquitous that analysts and police debate whether they are serving the public interest — or undermining public trust in law enforcement and even putting officers' lives in jeopardy. The videos are subjecting officers' actions in public places to new scrutiny and changing the way accusations against cops play out in court. In some communities, police are fighting back by enforcing laws that limit such recordings. Other departments are seeking new training for officers to prepare for the ever-present surveillance on the street. Just about every day, it seems, there is fresh video of cops engaged in controversial actions: Police slamming an unarmed man to the street in Denver. A college student thrashed by officers with batons during a University Maryland basketball victory celebration. An Oakland transit officer fatally shooting an unarmed man on a train platform. "There is no city not at risk of a video showing an officer doing something wrong," says San Jose Police Chief Rob Davis, president of the Major Cities Chiefs Association, a coalition representing the 56 largest cities in the USA. "The question, when one of these videos do surface, is what we do about it." In Illinois, Maryland and Massachusetts, some police have responded by trying to limit such recordings when they believe those recordings interfere with police actions. In Maryland, motorcyclist Anthony Graber was charged with felony violations of Maryland's wiretapping law for recording a March 5 encounter with a gun-brandishing state trooper during a traffic stop. The law requires both parties to consent to the recording of a private conversation. Graber faced a maximum 16-year prison sentence if convicted until Harford County Circuit Court Judge Emory Pitt threw out the case Sept. 27, saying, "Those of us who are public officials and are entrusted with the power of the state are ultimately accountable to the public." Some departments have sought training for officers to prepare them for increased surveillance of police activity. "All of our people should be conducting themselves like they are being recorded all the time," says Lt. Robin Larson, who oversees training for the 3,200-officer Broward County, Fla., Sheriff's Office, which once hired Kamau to help prepare new cadets by making them aware their actions could be taped and transmitted. Some police believe videotaping officers poses broad risks that reach beyond Internet embarrassments: It could cause officers to hesitate in life-threatening situations. "The proliferation of cheap video equipment is presenting a whole new dynamic for law enforcement," says Jim Pasco, executive director of the Fraternal Order of Police, the nation's largest police union. "It has had a chilling effect on some officers who are now afraid to act for fear of retribution by video. This has become a serious safety issue. I'm afraid something terrible will happen." Kamau and others argue terrible things already have occurred to victims of officer abuse, and video has brought some of the most brutal cases to the public's attention. Video also has helped narrow the "credibility gap" between police and their accusers, civil rights lawyer John Burris says. "It used to be that the police officer always got the benefit of the doubt," says Burris, who represented Rodney King in a civil lawsuit against the city of Los Angeles related to his videotaped beating by white Los Angeles police officers. Television broadcasts of the infamous tape, one of the first to show the power of citizen videos of police actions, prompted widespread public outrage. "The camera, increasingly, is offering a shock to the consciousness," Burris says. To ignore the effect of video on police credibility, Kamau says, is "like disregarding the influence of the Internet on political campaigns." "Things are changing dramatically," he says, "and police are not prepared for it." Video helps explain officer's actions Video has helped to resolve many cases of police misconduct, but such images also can present a more complex account of officer behavior. Former Oakland transit cop Johannes Mehserle is in jail awaiting sentencing on Nov. 5 in connection with the fatal shooting of Oscar Grant largely because the incident was captured on video. Yet video also is the reason, defense attorney Michael Rains says, that Mehserle was convicted July 8 of the lesser offense of involuntary manslaughter after he was charged with murdering the unarmed, 22-year-old train passenger. The criminal allegations followed transit officers' response to reports of fighting aboard a Bay Area Rapid Transit (BART) train in the early morning hours of New Year's Day 2009. Grant was among a group pulled off the train at a local stop, according to court documents. Mehserle and another officer had detained the group, the documents state, when Mehserle shot the unarmed Grant while the man's hands were cuffed behind his back in a scene captured by bystanders on cellphone and video cameras. The images of the shooting involving a white officer and a black victim quickly hit the Internet, where they prompted violent protests in Oakland and instant comparisons to the Rodney King case. "The King video went viral pretty quickly for back then," says Burris, who also represents the Grant family. "But this went as fast as anything could go. The outrage came much quicker." State prosecutors charged Mehserle with murder, and the case — because of its notoriety and local unrest — was moved to Los Angeles. Defense attorney Rains concedes the raw video initially had a "shocking effect" on jurors. "I tried to prepare them for it," he says. "I guess you don't get oblivious to seeing something like that." What did help Mehserle's case, Rains says, is that more than one video showed what happened that morning; six were introduced at trial. Taken together, Rains argued, the videos captured several angles and supported his client's claim that he meant to draw a stun gun but mistakenly pulled his .40-caliber handgun. Rains says his client's hand movements recorded on some of the videos were consistent with attempts to open the snap of the holster of his stun gun. "His body was doing things as if to draw and fire the Taser, not the gun," Rains says. More video, Rains says, shows Mehserle's "compelling" reaction after the shooting. "The video shows him throwing his hands to his head in shock," Rains says. "It was a terrible thing to happen. It was a tragedy it did." But the attorney says he was "very, very happy to have this video." Although Burris does not agree with the jury's apparent interpretation of the videos (jurors have not spoken publicly about their decision), he also is happy they exist. "Without the videos, there would have been no prosecution," he says. "It meant everything." A 'profound effect' on officers' actions David Allred, a former Justice Department official who prosecuted police misconduct cases for more than 30 years, says the proliferation of video in police cases is likely to have "a profound effect" on the long-term behavior of officers. "If you're prosecuting a case and you can find video to support it, it's just terrific," Allred says. "But often it's terrific for the police, as well, because it can just as easily exonerate officers. "The real impact, I think, is on what officers will do if they think they are being photographed." One of the most-viewed incidents — more than 200,000 views on YouTube— is a March encounter between a University of Maryland student and Prince George's County, Md., police officers during a celebration of a Maryland basketball victory. A video shows senior Jack McKenna approaching officers, who began pummeling him with batons. A police report alleged that McKenna had provoked the encounter by striking mounted officers and their horses, contrary to what is shown in the video. Three officers have been suspended and the case remains under investigation by Prince George's County and the Justice Department. In August, the city of Denver's public safety manager resigned and two officers were reassigned after questions surfaced about police conduct in at least two incidents captured on video. The incidents, which remain under investigation by Denver police, include an April 2009 encounter between police and two pedestrians, one of whom is shown being violently wrestled to the street. The encounter was recorded by a security camera mounted on a light pole and later landed the alleged victims on network morning news programs. "At this point, officers need to be constantly reminded that the potential for them to be on video or to be photographed is extraordinarily high," Pasco says. 'It embarrassed us' Larson, the Broward County Sheriff's Office training officer, says her agency knows firsthand the power of video and has learned from it. The lesson was delivered about three years ago by Kamau. While working for his private investigative firm policeabuse.com and a client, the former cop walked into one of the agency's reception areas with a hidden camera and found immediate problems with the way officers and employees dealt with the public. Kamau says police routinely provided incorrect information to people or couldn't answer basic questions about department policy, such as how to file a complaint against police. "It embarrassed us," Larson says, adding the video found its way to local television. Larson says the incident "sparked a lot of activity" within the agency, leading to changes in public reception area staffing, including retraining. Police officials also invited Kamau to help train new cadets. "Even though he could be viewed as the enemy, we were open to learning from the experience," she says. "If we screwed up, give us your thoughts on how we can make it better." Kamau, who helps clients resolve their grievances with police, says he counsels many of them to arm themselves with cameras to support their cases. "Video is making victims more credible," Kamau says. "If Rodney King would have tried to tell his story without video, nobody would have believed it." Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more