According to experts, it all comes down to education and experience.
According to the Brooklyn Center police chief, the suburban Minneapolis police officer followed standard police policy, announcing she was about to discharge her Taser-warning nearby officers of the imminent shock charge.
RELATED: Minnesota police chief says officer meant to draw Taser, not gun in fatal Brooklyn Center shooting
She could be heard yelling on body camera video, "I'll tase you! I'll tase you! Taser! Taser! Taser!"
But she had drawn her handgun instead, according to the chief; firing one round, mistakenly killing instead of subduing 20-year-old Wright, who was being arrested on an outstanding warrant.
"She said, 'Holy something, I shot this guy...'" Brooklyn Center Police Chief Tim Gannon said..
The duty belts worn by law enforcement officers are jammed with weapons, ammo, and other accessories. Law enforcement expert and former longtime Des Plaines Police Chief Bill Kushner said officers are instructed to holster their gun and their Taser on opposite sides of their duty belt.
"Because you develop a muscle memory going for your firearm, you don't want to have the Taser mounted in front or behind you, because your firearm is a lethal weapon," Kushner explained. "You want the Taser mounted somewhere where it's a distinct movement away from the firearm. Okay, so there will be a cross draw holster if you're a right handed individual you want it mounted on the left side of your body, in a cross draw fashion."
The latest Chicago police policy spells out: "Taser Devices will be carried in a Department-approved holster on the member's support (non-firearm) side."
But on rare occasions, young or inexperienced officers can grab the wrong tool, even though a 9mm handgun weighs about 34 ounces and a stun gun weighs 8 ounces.
"It's got a different grip feel to it, the weight is different. Firearms kind of sit more in the hand back in the palm of your hand," Kushner said.
What happened in Minnesota, he added, should not have gotten to the level of a fatality.
Most police departments have recurring training for Taser use, sometimes quarterly. But there is a difference between learning and doing, and investigators in Minnesota will be looking at when that officer was last re-certified with a Taser, what the refresher course looked like and whether her department had ongoing training for dealing with stressful situations.