A decade ago, Minneapolis police officers used Tasers in a quarter of all use of force incidents per year, according to data from the city of Minneapolis. Now that percentage is about half that. St. Paul officers have also decreased their use of Tasers from 233 deployments in 2009 to just 38 last year.
MPR News requested data from both departments on Taser use after an APM Reports investigation found the devices weren't as effective as the device maker markets them to be.
However, Minneapolis and St. Paul police did not provide data on Taser failures because they don't collect them. And the departments were not a part of APM Reports' analysis.
Lt. Johnny Mercil of the Minneapolis Police Department said in his experience, there's one main reason Tasers don't always work the way they're supposed to.
"In our climate, the No. 1 problem we have with the Tasers is that people have multiple layers of clothing on just to survive living in this state for six months a year," said Mercil.
Tasers have two metal-tipped darts attached to metal cables. The darts need to make contact with a person's skin or clothing near the skin to transmit a jolt of electricity. Officers are trained to fire Tasers from 8 to 9 feet away. Ideally, the darts will attach to their target about 12 inches from each other.
Mercil said the Taser is most effective when it runs electricity through a larger portion of the target's body.
Officer Chad Malmberg of the St. Paul Police Department said the darts don't need to pierce the skin to be effective. He said as long as the darts are close to the skin, the electricity generated by the device will stun the person.
Both Malmberg and Mercil say there's more emphasis placed on avoiding physical confrontations. Officers are trained to take their time in defusing a volatile situation — or, when possible, to back off and give someone space so as to not force a confrontation.
Sometimes, said Malmberg, a successful Taser deployment doesn't necessarily mean that an officer used the device to shock someone. He said just displaying a Taser can persuade an unruly person to comply with the officer.
"If we're able to de-escalate them just by demonstrating a spark display or even just aiming at them with the red dot that's used to sight the device and then de-escalate that behavior, then that would be ideal circumstances for us and for everybody," he said.
• APM Reports documentary: When Tasers Fail
• Jan. 29: Minneapolis man with mental illness sues city over Taser use
The spark display Malmberg mentioned is a function of the device. The operator can generate bolts of electricity which makes a loud buzzing sound.
Although a "successful" deployment of Taser darts can deliver a painful and incapacitating shock, as the APM Reports investigation found, sometimes people in a heightened state of mental health crises or drug intoxication respond differently. In some cases, the shock can make them angrier and cause officers to then use the most lethal weapon they have: their guns.
However, both Mercil and Malmberg say Tasers are useful tools. And they haven't heard officers complain about ineffectiveness. Mercil said the goal is to protect the lives of officers and the public.
"If the Taser doesn't work, their life is in more danger," said Mercil. "Our life is in more danger."