The June 2 editorial “An unexplained death at Costco,” on the death of a woman who allegedly attempted to stab Loudoun County sheriff’s deputies, reflects a widespread misunderstanding of the Taser’s capabilities.

While The Post claims that the Taser “almost always incapacitates the subject,” my experience as a police sergeant and Taser instructor is far different. As effective as the Taser usually is, it does sometimes fail.

The Taser discharges two probes at different angles. If one or both probes miss the target, the Taser will not work. Given that both the officer and the threatening person may be moving when the Taser is deployed, misses occur frequently. Even if both probes hit the target, one or both can become dislodged by movement, rendering the Taser ineffective. If the probes hit fatty tissue or loose clothing, the effectiveness is reduced. Lastly, some people, especially the mentally ill and those under the influence of drugs, are unaffected by the Taser, no matter how unlikely The Post thinks this is.

By all accounts, Mhai Scott was armed with a long-bladed knife and scissors. At close range, an edged weapon is just as deadly as a firearm. While Tasers have been used to subdue knife-armed subjects, Taser International’s own doctrine advises that an officer should anticipate failure and be supported by a colleague, with his firearm drawn, ready to shoot.

The death of Ms. Scott is certainly a tragedy, but it is not the fault of the Loudoun County Sheriff’s Office or Taser International. Indeed, the deputies should be commended for their restraint in attempting to use a less lethal weapon to subdue a deadly threat.

John Converse, Rockville