New study fuels debate on Taser safety - 9% of stun guns in study gave more powerful jolt

December 5, 2008
Ronald J. Hansen and Robert Anglen, The Arizona Republic

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., also concluded that even stun guns firing at expected electrical levels carry some risk of inducing a heart attack, depending on the circumstances.

The researchers' analysis contradicts Taser's position that electric shocks from the weapons cannot kill. The study said the results raise questions about quality control in the stun gun's manufacturing and decline in performance over time.

Taser International Inc., based in Scottsdale, 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 study, which authors say tested more Tasers than any previous independent review, examined 44 stun guns being used today by U.S. law-enforcement agencies. It found that four would not fire at all or fired improperly and that four others produced from 47 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 X26 stun guns made before 2005. They also recommended more electrical tests on Tasers now in use by Canadian and U.S. law enforcement.

Pierre Savard, a biomedical engineer in Montreal who co-authored the report with two Chicago doctors, said they may 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 added that 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 said in an interview with The Arizona Republic. "I'm 100 percent certain that cardiac diseases increase the risk of death after receiving Taser shock. I think there's enough scientific evidence for that."

It's still unknown if illegal drugs also change the risk factor, Savard added.

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.

The safety issue

The guns are used by more than 12,000 police agencies across the country, including every major law-enforcement agency in the Valley. 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.

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. "The device is calibrated such that it cannot output any more power. It's running at 100 percent," Taser Chief Executive Officer Tom Smith testified in May during a British Columbia government inquiry into Taser safety.

The inquiry was spurred by the 2007 death of a Polish citizen at Vancouver International Airport who stopped breathing within moments of being shocked twice by police.

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.

"We do not recommend (agencies') testing the output," Smith said at the hearing.

Valley police agencies contacted Thursday confirmed that they did not conduct any independent electrical tests on the stun gun before arming officers. Both Phoenix and Chandler police departments issued statements saying they were not aware of the study and will review its validity and reliability.

"We are going to take a look at the study and evaluate it," Chandler Detective David Ramer said. "Anytime something like this comes out, we look at it."

The 44 Tasers used in the recent study were obtained from seven undisclosed U.S. police agencies. Canada's national public-television and -radio broadcaster, the Canadian Broadcasting Corp., paid for the study as part of its ongoing investigation of Taser.

CBC hired National Technical Systems, a California-based firm that tests weapons systems for the U.S. military. It found that four of the X26 guns fired more electrical current at their peak than Taser guidelines show is possible for that model. Three other guns didn't fire at all, and one couldn't sustain its current properly. The rest fired within the guidelines.

The tests were based on Taser's own testing protocol and the electrical-load level recommended by Taser. Each stun gun was tested six times and the results were inconsistent, Savard said, raising manufacturing concerns.

"Since 67 percent of the older devices . . . showed this type of problem, this raises the issues of quality control during manufacturing and component aging," Savard wrote in the report.

In other tests at different load levels, Savard said, all of the four Tasers that showed excessive current fired within normal ranges.

All four of those that fired beyond their expected capacity were sold to two police departments in 2004, making them among the oldest tested. That raised questions about how the guns age and how they were made in the first place, Savard said.

Magne Nerheim, Taser's vice president, challenged the study on significant areas. He said researchers failed to spark-test the gun before testing the power, which created exaggerated results "not representative of actual output." He also said the guns were tested using an incorrect resistance level that does not reflect the effect of Taser shocks on a human.

Resistance, measured in ohms, refers to how any object withstands an electrical charge. The higher the resistance level, the less effect the charge will have. Nerheim said if the resistance level had been increased, the guns would not have recorded such powerful shocks.

Nerheim's challenges, however, differ from a protocol that Taser sent this year to Canadian police officers who were testing Tasers used on a suspect who died after being shocked.

The testing protocol, obtained by the CBC, specified using the lower resistance level, the same one NTS followed for its study.

The protocol Taser sent to police also made no mention of conducting a spark test. A spark test is an initial pull of the trigger. "Inside the device, it takes a higher initial voltage to wake up the component that has become inactive from not being regularly operated," Nerheim said.

But Taser is not consistent in its spark-test recommendations. The company tells police to conduct a test every day on the X26, but the operating manual for the consumer model (X26C), which is modeled after the police version, says a test is needed once every six months.

Nerheim stressed that the study concentrated only on the first pulse of the stun gun, which fires 19 electrical pulses per second, and suggested averaging all the pulses over the span of a second would offer a more relevant safety picture.

In any event, he said the first pulse would not reach a person shot with the device's darts. Nerheim didn't address how an overly high initial pulse would affect someone shocked by direct contact with the gun, one of the methods used by police.

Taser officials did not address findings concerning the age of the guns that fired at abnormally high levels.

Design and manufacturing issues have surfaced before on the stun guns.

"Design flaws and manufacturing-process problems" were key elements in a shareholder lawsuit against Taser in 2005. The lawsuit alleged that faulty quality control and unstable circuit boards led to major returns of Tasers, and a former employee testified that "as much as 70 percent of the M26 and X26 (Taser models) tested in-house by Taser were defective."

Taser settled the lawsuit in 2006 for $21 million, but company officials steadfastly denied the accusations, describing the payout as a business move and a way to avoid expensive litigation.

Effects on the heart

The doctors and engineers hired by the CBC to interpret the results determined the higher electrical current was enough to raise the risk of an irregular heartbeat to as much as 50 percent for those with existing heart troubles.

The risk level depends on various factors, including whether the heart lies between the Taser's barbs and how long the shock lasts. The risk would decline if, for example, the Taser's barbs fell off or didn't fully penetrate the skin.

Savard also concluded that multiple shocks from normally working Tasers posed up to a 5 percent risk of ventricular fibrillation, the abnormal heart rhythm associated with a heart attack.

Savard said he is worries that police are given Tasers that are potentially deadly but are told they are totally safe. He suspects such pronouncements have led to a dangerous "drift" in usage of the weapons.

"If you're told there's zero risk . . . you can start using it just to save time because you're tired of talking with the subject," he said.

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