A study published by the American Journal of Cardiology found that California police departments that introduced Tasers experienced significant increases in the numbers of in-custody sudden deaths and firearm deaths in the first full year following deployment. The rates declined to predeployment levels in subsequent years. No significant change in the number of officer injuries was found.
A study by the Potomac Institute concluded; “Based on the available evidence, and on accepted criteria for defining product risk vs. efficacy, we believe that when stun technology is appropriately applied, it is relatively safe and clearly effective. The only known field data that are available suggest that the odds are, at worst, one in one thousand that a stun device would contribute to (and this does not imply “cause”) death. This figure is likely not different than the odds of death when stun devices are not used, but when other multiple force measures are. A more defensible figure is one in one hundred thousand.”
After hearing many witnesses and briefs the report by the Canadian House of Commons, Standing Committee on Public Safety and National Security makes 17 recommendations as a result the death due to the repetitive tasering of a Polish immigrant at the Vancouver International airport.
An investigation by the Canadian Press and Canadian Broadcasting Corporation found that one-third of those shot by a Taser by the Royal Canadian Mounted Police received injuries that required medical attention as a result. The news agencies used Freedom of Information requests to obtain the Taser-use forms filled out by RCMP officers from 2002 to 2007.
The study done by Pierre Savard, Ing., PhD., Ecole Polythechnique de Montreal, et al., for the Canadian Broadcasting Corporation (CBC), indicated that the threshold of energy needed to induce deadly ventricular fibrillation decreased dramatically with each successive burst of pulses. The threshold for women may be less .
Although the TASER is a programmable device, the controlling software does not limit: a) the number of the bursts of pulses and the time between bursts while the trigger is held down continuously, or b) the number of times the shock cycles can be repeated. Thus the design does not adequately reduce the likelihood that the victim’s heart enters into a deadly ventricular fibrillation.
According to a study presented at the Heart Rhythm Society’s 2007 Scientific Sessions, Tasers may present risks to subjects with implanted pacemakers. However, a study conducted by the Cleveland Clinic in 2007 on a single animal determined that a standard five-second TASER X26 application “does not affect the short-term functional integrity of implantable pacemakers and defibrillators… The long-term effects were not assessed.”
A Chicago study suggests that use of the Taser can interfere with heart function. A team of scientists and doctors at the Cook County hospital trauma center stunned 6 pigs with two 40-second Taser discharges across the chest. Every animal was left with heart rhythm problems and two of the subjects died of cardiac arrest. One of the subjects died three minutes after being shot indicating, according to researcher Bob Walker, that “after the Taser shock ends, there can still be effects that can be evoked and you can still see cardiac effects.”
In 2006, the US National Institute of Justice began a two-year study into taser-related deaths in custody.
San Francisco cardiologist and electrophysiologist Dr. Zian Tseng told the Braidwood Inquiry that a healthy individual could die from a Taser discharge, depending on electrode placement on the chest and pulse timing. He said that the risk of serious injury or death is increased by the number of activations, adrenaline or drugs in the bloodstream, and a susceptible medical history. After Tseng began researching Tasers three years ago, Taser International contacted him, asking him to reconsider his media statements and offering funding.
A February 2005 memorandum from the Aberdeen Proving Ground, a United States Army weapons test site, discouraged shocking soldiers with Tasers in training, contrary to Taser International’s recommendations. The Army’s occupational health sciences director affirmed the Taser’s effectiveness, but warned that “Seizures and ventricular fibrillation can be induced by the electric current.” and that “the practice of using these weapons on U.S. Army military and civilian forces in training is not recommended, given the potential risks.”
A study conducted by electrical engineer James Ruggieri and published January 2006 in the Journal of the National Academy of Forensic Engineers measured a Taser’s output as 39 times more powerful than specified. The study concluded that the discharge is sufficient to trigger ventricular fibrillation, a 50 percent risk according to electric safety standards. Ruggieri said that electricity breaks down skin tissue, decreasing its resistance and increasing current through the body.