Today, most police officers in America carry a Taser. The manufacturer says Tasers allow cops to resolve dangerous situations without using their guns. But they don't always work.
"When Tasers Fail" is a new documentary by Curtis Gilbert of the APM Reports documentary unit, produced with the Center for Investigative Reporting, Reveal and PRX.
Tasers have become an essential tool for police, but how effective are they?
An APM Reports investigation finds that officers in some big cities rated Tasers as unreliable up to 40 percent of the time, and in three large departments, newer models were less effective than older ones.
In 258 cases over three years, a Taser failed to subdue someone who was then shot and killed by police.