A new study has found that the type of Taser stun gun used most by police officers can fire more electricity than the company says is possible, which the study's authors say raises the risk of cardiac arrest as much as 50 percent in some people.
The study, led by a Montreal biomedical engineer and a U.S. defense contractor at the request of the Canadian Broadcasting Corp., concluded that even stun guns firing at expected electrical levels carry some risk of inducing a heart attack, depending on the circumstances. The study said the results raise questions about quality control in the stun gun's manufacturing and decline in performance over time.
The researchers' analysis contradicts Taser's position that electric shocks from the weapons cannot kill.
Taser International Inc., based in Scottsdale, Ariz., called the study flawed.
"Regardless of whether or not the anomaly (high-firing guns) is accurate, it has no bearing on safety," Taser Vice President Steve Tuttle said.
The guns are used by more than 12,000 police agencies across the country. Many authorities credit the weapon with preventing deaths and injuries to officers and suspects.
But since 2001, there have been more than 380 deaths following police Taser strikes in the United States and 26 in Canada. Medical examiners have ruled that a Taser was a cause, contributing factor or could not be ruled out in more than 30 of those deaths.
Taser has challenged those findings and maintains the stun gun is safe.
Canadian Broadcasting Corp., Canada's national public-television and radio broadcaster, paid for the study as part of an ongoing investigation of Taser.
The study, which authors say tested more Tasers than any previous independent review, examined 44 stun guns being used today by seven undisclosed U.S. police agencies. It found that four would not fire at all or fired improperly and that four others produced from 47 percent to 58 percent more power than the manufacturer specified.
Researchers said the fact that 9 percent of the guns tested abnormally high was significant enough to recommend a freeze in using Taser X26 stun guns made before 2005. They also recommended more electrical tests on Tasers now in use by Canadian and U.S. law enforcement.
CBC hired National Technical Systems, a California-based firm that tests weapons systems for the U.S. military, to collect data on the stun guns. The data was analyzed by Pierre Savard, a biomedical engineer in Montreal, and two Chicago doctors.
Savard said they might have understated the risk Tasers pose because there is little available research on the effects of the weapon on humans, especially those who have heart disease. Although Savard said he recognizes the value of less-lethal weapons, he said he is convinced Tasers can kill in some circumstances.
"Scientists who had evaluated the Taser to start with said, 'Well, there's zero probability of death.' I'm sure that's not the case," Savard told The Arizona Republic.
"I'm 100 percent certain that cardiac diseases increase the risk of death after receiving Taser shock."
Taser officials acknowledged the possibility of a higher-than-normal initial charge in weapons not first given a "spark test" to ensure they are in proper working condition. They insist this does not affect safety and cautioned Canadian Broadcasting in a memo not to use "engineering minutiae to confuse the (public) and create a false sense of controversy."
The study fuels a long-standing debate within medical and law enforcement circles about the safety of Taser's stun guns.
Taser executives have said for years that the guns could not produce shocks greater than the manufacturer's specifications and that the stun gun would melt before producing high-level shocks.
Law enforcement agencies that use Tasers typically do not conduct their own testing of the gun's discharge or safety but rely instead on the company's testing.
