Deadly police shootings across the country are forcing some big city police departments to take a new look at whether stun guns — typically called Tasers — could reduce the number of fatal encounters between officers and the public.

Last month, for example, Chicago Mayor Rahm Emanuel announced plans to buy hundreds of additional Tasers for his city’s police department and ensure every officer is trained to use them by June. The plans followed heated protests after a dashboard video showed an officer shooting a fleeing teen 16 times in a 2014 confrontation.

But equipping all police officers with Tasers is expensive, and the evidence that the devices reduce the number of officer-involved shootings is mixed: A 2010 expansion of Tasers in Chicago failed to produce a dip in police shootings. In addition, Tasers themselves also have proved to be deadly at times.

Though law enforcement analysts concede that Tasers are not a perfect solution, some say it is inevitable that alternatives to deadly force will get a longer look within major departments, including Minneapolis and St. Paul.

“They are going to have to budget for that,” said Jeff Garland, a defense tactics instructor at Hennepin Technical College who spent 31 years in law enforcement. “If they don’t look at alternatives, the other alternative is like in Ferguson, Cleveland and Baltimore: You’re going to be paying a heck of a lot more money with wrongful-death suits.”

Cost a factor

In Minneapolis — itself dealing with ongoing unrest after police in November shot Jamar Clark, an unarmed black man they say was reaching for an officer’s gun — just 60 percent of the department’s patrol officers are equipped with one of the 300 devices available, according to spokesman John Elder.

“Cost is certainly a factor,” said Elder, adding that the devices can run up to $1,500 per officer.

In St. Paul, where most officers have carried Tasers since 2010, occasions in which officers shot a firearm at suspects averaged more than five a year from 2012 to 2014, resulting in six deaths. Sgt. Mike Ernster, a St. Paul Police spokesman, said the department trained every officer to use Tasers in 2008 and began issuing them to every new police academy cadet in 2010.

Most of the 10 percent of those still unequipped, Ernster said, are older officers who have the option of being trained.

Tasers don’t guarantee non-deadly encounters, however. A Star Tribune database of deaths after police use of force since 2000 includes more than a dozen deaths after encounters in which a Taser was used — though some cases also involved guns.

One man died when he fell and hit his head after an officer tased him. Another “experienced a medical event” and died. A 76-year-old nursing home patient died after being tased and a 26-year-old’s heart stopped on the way to jail.

The Minneapolis Police Department tweaked its Taser policy in 2010 to characterize the device as “less lethal” instead of “nonlethal.” Studies and U.S. Supreme Court decisions influenced Taser guidelines advising officers not to use the device on a person for longer than five seconds at a time. Minneapolis’ revised policy cautioned that “exposure to multiple applications of the [Taser] for longer than 15 seconds may increase the risk of serious injury or death.”

A 2014 study published by the American Heart Association said the devices can cause cardiac arrest if used for too long or on people with certain medical conditions. The study said police should treat Tasers “with the same level of respect as a firearm.”

Garland said the “five-second window” created by a Taser shock creates an expectation that the officer will have time to take the suspect in custody.

“If you give someone a five-second ride, if you do that more than three times you’re going to have to justify why you didn’t do other things to keep that person on the ground,” Garland said.

Asked if there was a more effective way than a Taser to avoid the need for lethal force, Elder said “officers respond to hundreds of different and individual situations, presenting dozens of unique and situational variables.”

For Burnsville Police Chief Eric Gieseke, anything short of a gun-wielding suspect is an opportunity to first consider alternative means of resolving the confrontation.

“We train them that if you confront someone with a gun, you have to meet them with the same force,” Gieseke said. “[But] firearms are a last resort for us; if there’s anything in between there to gain control, we consider that a success.”

Two Burnsville officers notched one such victory in 2008 when responding to a man threatening family members with a meat cleaver. “Chanting about God and repenting to Jesus,” the man plunged the cleaver into the wall and took up a fighting stance in defiance of officers’ commands, Gieseke said. He said the officers, Nicholas Larson and Dallas Moeller, tased the man long enough to disarm and secure him, later earning awards for valor from the department.

Gieseke has lately tallied not only how often Tasers are used but whether officers resorted to the devices after pulling them out. Tasers represented nearly half of all use-of-force events since 2013, Gieseke said. Over that time, calls involving the use of a Taser dropped from 66 percent of all encounters in which the device was pulled to just a third last year.

“I think a big part of that is people know,” Shakopee Police Chief Jeff Tate added. “Just having the Taser out can de-escalate. They see that and they back down,” he said of suspects.

Shakopee officers deployed their Tasers just five times last year, Tate said.

Tasers may not be a perfect option, said Garland, the defense instructor, who said thick winter clothing may make it difficult for the device’s prongs to strike skin. But given the current challenges in police-community relations, Garland said Tasers and other alternatives, like beanbag guns or devices that shoot nets, will warrant a closer look.

“Before if it was not a priority,” he said, “now I think it will be.”