A new study says the obvious: suspects' brains are briefly scrambled when they are on the receiving end of a Taser stun gun and its 50,000-volt delivery. But the study, "TASER Exposure and Cognitive Impairment: Implications for Valid Miranda Waivers and the Timing of Police Custodial Interrogations," (PDF) questions whether suspects who were just shocked have the mental capacity to validly waive their Miranda rights and submit to police questioning.

"TASER-exposed participants resembled patients with mild cognitive impairment, which suggests that not only might our participants be more likely to waive their Miranda rights directly after TASER exposure, but also they would be more likely to give inaccurate information to investigators," reads the study, which appears in the journal Criminology & Public Policy. "Thus, part of our findings implicates a suspect’s ability to issue a valid waiver, whereas another part implicates the accuracy of information he or she might give investigators during a custodial interrogation (e.g., false confessions or statements)."

The paper said that police departments might want to wait to question a suspect for about an hour, the amount of time for brain functioning to return to normal after a suspect is shocked. The Drexel University and Arizona State University researchers said innocent suspects may not appear so innocent right after being shocked:

The problem is that even innocent suspects who waive their Miranda rights could make incriminating statements that become difficult to explain away as they progress through the interrogation process. To the extent that TASER-exposed suspects experience cognitive declines that inhibit their ability (at least in the short term) to process adequately the consequences of waiving their Miranda rights, they too may become susceptible to suggestibility or memory lapses right after hearing their rights. They may waive their Miranda rights and make incriminating statements to police without the benefit of counsel. Those statements might be inaccurate or untrustworthy (based on short-term memory impairment) given their declines in cognitive abilities.

Researchers said they recruited 142 participants randomly placed in four groups. A control group of 37 participants did nothing. Another group of 32 people hit a punching bag "to simulate the heightened physical state one might expect in a tense police encounter." A group of 35 people received five-second shocks and 38 people received five-second shocks and also hit a punching bag. The testing of "healthy college students" was done at a hospital. Most screamed when being shocked and also used profanity.

The study said:

Indeed, it is likely, if not probable, that this group of relatively young, healthy, well-educated, frequent test takers, who were sober and drug free at the time of their TASER exposure, function on average at a much higher level of cognition than do the "typical" suspects in the field who experience TASER exposure at the hands of police officers. Thus, given the declines in cognitive functioning experienced by the present study’s participants, we would expect "typical" suspects—who may be drunk, high, or mentally ill and in crisis at the time of exposure—to experience even greater impairment to cognitive functioning as the result of TASER exposure.

The report, funded by the Justice Department, noted that 17,000 police departments across the US have used stun guns on more than 2 million people the past decade. Because of those large numbers, there was a moral imperative to conduct the study, said one of the researchers, Robert J. Kane, a professor and director of the Criminology and Justice Studies Department in Drexel's College of Arts and Sciences.

"The findings of this study have considerable implications for how the police administer Miranda warnings," said Kane. "If suspects are cognitively impaired after being tased, when should police begin asking them questions? There are plenty of people in prison who were tased and then immediately questioned. Were they intellectually capable of giving 'knowing' and 'valid' waivers of their Miranda rights before being subjected to a police interrogation? We felt we had moral imperative to fully understand the Tasers' potential impact on decision-making faculties in order to protect individuals' due process rights," he said.

The paper was quick to point out that it is not indicting Taser's products, saying instead that stun guns are a "reasonable alternative to physical force." However, hundreds of deaths have been linked to those being targeted by a stun gun.