Before a bystander's video led to his murder charge and firing, North Charleston Police Officer Michael Slager said he killed a fleeing suspect in a traffic stop after a struggle over his Taser.
Along with other worrisome aspects of the shooting of Walter Scott, Slager's attempt to subdue him with a stun gun points to a policing paradox that has civil rights advocates alarmed.
Promoted as tools to avoid lethal force, stun guns can sometimes become part of a deadly equation. The Associated Press found at least seven other fatal shootings of black men by police in confrontations involving stun guns in recent years.
These immobilizing weapons are useful, but can give officers "a really false reassurance that you have more control over a situation than you do," said Eugene O'Donnell, a former New York City police officer who now teaches at the city's John Jay College of Criminal Justice.
Slager was charged with murder and fired from the North Charleston Police Department after a bystander's iPhone video captured him shooting a fleeing Walter Scott in the back after failing to subdue him with a Taser.
"Officers need to be spending more time de-escalating situations, instead of resorting to the use of this very convenient tool," said Emma Andersson, a staff attorney with the American Civil Liberties Union. "The jury's still out on whether or not it's lethal force, but it's not nothing; it's very dangerous."
Stun guns have become an extremely common policing tool, deployed in more than 15,000 U.S. law enforcement and military agencies, according to a 2011 National Institute of Justice report. TASER International Inc. says it has sold more than 800,000 of its devices to law enforcement agencies, which have used them more than 2.3 million times in the past 20 years.
The overall record shows Tasers are "safe, effective and accountable," said Steve Tuttle, a spokesman for the Scottsdale, Arizona-based company. "But it's not a magic bullet. ... There is no magic bullet."
Stun guns can save lives by enabling officers to subdue people without serious injuries, although the ACLU and Amnesty International say hundreds have died from the shocks alone. The device's makers counter that Tasers are safe against otherwise healthy targets if not used repeatedly.
Still, the potential for deadly consequences has prompted many law enforcement agencies to strictly limit how officers use them. Stun guns "should be used as a weapon of need, not a tool of convenience," say guidelines developed in 2011 by the U.S. Justice Department.
The National Institute of Justice report found that field experience with stun guns indicates that short-term exposure is safe in the vast majority of cases.
But NIJ-funded research in 2012 from Michigan State University, looking at more than 10,000 use-of-force cases in a half-dozen cities, came to a more nuanced conclusion: Stun guns make citizen injuries more frequent, even as they halve the rate of injuries to officers, from 10 percent to 5 percent. Citizens are injured 41 percent of the time when stun guns are used to subdue them, compared to 29 percent when they weren't, the report said.
Some police agencies have adopted polices in line with the ACLU's key recommendation: that Tasers should only be used to counter an immediate threat to life or safety, as an alternative to deadly force.
The Taser policy North Charleston issued in 2009 sets a much lower standard: Officers may use a stun gun "to take a subject into custody" or overcome "passive physical resistance" from a person who "does not make any attempt to physically defeat the officer."
North Charleston does require officers to file a report when they use a Taser, but it has not said whether any resulting numbers suggest they have reduced or increased the use of force. The department has not responded to Associated Press requests for these and other records following Scott's shooting.
Visitors to the makeshift memorial near the spot where Scott died say the city's police became overly quick to use force after adding stun guns to their tool belts.
"I think years ago there was more patience involved, more negotiating, more talking. Now I think because of the Tasers, it may give them an easier defense — they may use it quicker," Arvetra Jones said Monday while viewing the flowers and signs people had stuffed into a chain-link fence.
Stun guns — along with traffic stops for minor offenses and law enforcement blitzes of poor neighborhoods — have become another reason to fear police, said James Johnson, president of the Charleston area chapter of the Rev. Al Sharpton's National Action Network.
"They become afraid. They don't want to be tased again. That is some very sharp pain if it is going to stop a 300-pound man," Johnson said.
He's hoping that when North Charleston requires each officer to use body cameras, stun gun cases will decrease.
His advice meanwhile? "Be calm. Tell police, 'Please don't tase me.' Hopefully with the body camera, the officer will think twice," Johnson said.
Slager is accused of twice using his stun gun against people who posed no physical threat. Mario Givens filed a formal complaint with the North Charleston police in 2013 saying Slager shocked him for no reason, but the case was closed and the officer exonerated. On Friday, Julius Wilson sued Slager, the police and the city, alleging that he was pulled from his vehicle and shot with a Taser by Slager even though he was cooperating.
Jeffrey Collins reported from Columbia. Contributors include Bruce Smith in Charleston, South Carolina; Michael Biesecker in Raleigh, North Carolina; Jennifer Peltz in New York and Corey Williams in Detroit.