Israel Hernandez-Llach was armed with a can of spray paint. He was 18 years old, 5 feet 6, 150 pounds. He was spraying the letter “R” at 5 a.m. on a shuttered McDonald’s in Miami Beach, Florida, and when the cops pulled up, he bolted. Now he’s dead.

The burgeoning artist was known throughout the community and in some circles across the country. A police report obtained by the Miami Herald indicates that the teenager led officers on a zigzag chase to avoid capture, skirting through buildings and up and down alleys. When finally cornered a block away, Hernandez-Llach bolted straight at the officers, at which point Officer Jorge Mercado deployed a Taser. It struck Hernandez-Llach in the chest. An hour later, he was pronounced dead at a nearby hospital.

To some activists and residents in Miami and beyond, the artist’s death is a tragic reminder of excessive force at the hands of local police, bringing back memories of a 2011 incident when a man pulled over for driving erratically wound up dead after six officers fired 100 bullets into his car, injuring multiple bystanders. Others say at issue is the improper and excessive use of the Taser itself. Amnesty International says that since 2001 more than 500 people have been killed in the U.S. after being shocked by a Taser. Of those, more than 60 were listed by medical examiners as being directly attributable to the device; others had a cause of death unknown.

Amnesty says Tasers have become tools of the lazy cop who wants a suspect down in an instant, a tool that police have been told so often is “nonlethal” that they have come to use it without much regard for why they’re firing it or where they’re aiming.

The problem, said Suzanne Trimel, a spokeswoman for Amnesty International, is that police have come to rely on Tasers as a “weapon of first resort.” “They were introduced as a nonlethal equivalent of firearms, but more and more they’re used when firearms wouldn’t even be justified,” she said.

Steve Tuttle, a spokesman for the Scottsdale, Arizona-based Taser Inc., dismissed that criticism in an interview with The Daily Beast. The vast majority of Taser deployments don’t result in any injury, he said, adding that the same can’t be said of other tools at an officer’s disposal—the nightstick, the clenched fist, pepper spray, or revolver.

“This means we’ve gotten away from beating somebody into submission,” Tuttle said. But the device isn’t a “magic bullet,” he added. “Is it the right tool for every situation? It sure isn’t.”

What has organizations like Amnesty International calling for a moratorium on police use of Tasers is the scarcity of training for officers nationwide and lack of uniform protocol about how and when to use them.

The Miami Beach Police Department protocol for use of the M-26 Taser, for example, requires officers to use it only “in an arrest situation when a subject fails to comply with verbal commands and [emphasis theirs] physically resists efforts to effect an arrest, or to debilitate a subject to prevent serious injury to others.” Taser use isn’t warranted for “passive physical resistance or a single act of verbal non-compliance.”

The policy prohibits using a Taser if flammable gases or liquids are nearby, or if it could trigger a fall from an elevated location or into deep water. Also banned are Taser use on a pregnant woman, young children, or the elderly, “unless deadly force is justified.” The policy says nothing about avoiding the chest.

That element is critical, said Douglas Zipes, a cardiologist at Indiana University whose research has linked Taser deaths to cardiac arrest.

“The whole concept is so concretely established in what we already know,” he said.

Tasers fired at the chest can operate in the same way doctors sometimes stimulate a lagging heart via a procedure called cutaneous pacing. The difference with a Taser, though, is that it delivers jolts to the heart at a rate of 1,100 times per minute, versus the 70 to 80 involved in pacing, says Zipes.

What Zipes said he finds remarkable is that anyone disputes that idea. While Tuttle acknowledged that Taser Inc. recommends avoiding the chest “when possible,” he also added that “it’s not a ‘shall not.’” Asked why that recommendation exists, he cited “a theory several years ago out there that shots to the chest may have some cardiac implications. We put this out in a warning. Like any good company, we’ve got to be concerned about litigious behavior.”

In other words, it’s not that Tasers cause heart attacks. It’s just that the company doesn’t want to get sued if someone has a heart attack after being Tased.

But that litigation threat—and the filing of multiple lawsuits in the wake of Taser-related deaths—has begun to have an effect in the law enforcement community, said Chuck Drago, a former police chief and law enforcement consultant in Florida.

“In the beginning, with any amount of resistance you could use a Taser,” he said. “That’s why you heard about cases where the officer says, ‘You’re under arrest,’ and somebody goes, ‘You can’t arrest me!’ and bam. They’d hit him with a Taser. That’s a lot less likely to happen today.”

Now police have begun using the Taser only as a response to physical violence. The International Association of Chiefs of Police has issued guidelines that suggest Tasers should be used not just in the case of a person running from police but when a person is “either using physical force or it appears to be imminent,” Drago said. “Departments are toning it back, as they realize the Taser may not be as innocent a weapon as it was broadcast to be in the beginning.”

Some departments have banned officers from using Tasers altogether, although Tuttle contended that in most of those cases, the Tasers returned after the agency took the time to study the issue and retrain the force.

What’s needed now is much more training and education, argued Zipes, who said he is not against the use of the Taser by police. Lesson No. 1, he said: “Avoid the chest. If that were implemented in Miami, this youngster would not have died.”

Editor's Note: Tasers fired at the chest don't act like defibrillators. An earlier version of this story incorrectly said they did. Also, more than 500 people have died in the U.S. since 2011 after being shocked by a Taser, according to Amnesty International. Of these, more than 60 were attributed by medical examiners directly to Tasers. An earlier version said all these deaths were caused by Tasers.