Even as police departments across the country embraced Taser stun guns over the past 15 years, the New York Police Department kept them out of the hands of almost all officers. Only some sergeants and members of a specially trained unit were issued the handgun-shaped weapons, and regulations required many of them to keep the devices in the trunks of patrol cars.

The restrictions were rooted in the department’s troubled history with an earlier generation of stun guns, most notably an episode 30 years ago in which officers in a Queens precinct tortured prisoners with one. More recently, in 2008, an officer with the elite Emergency Services Unit fired a Taser at an emotionally disturbed man on a ledge in Brooklyn. The man fell some 10 feet to his death, and the lieutenant who had given the order to fire the Taser committed suicide eight days later.

Now the Police Department, under different leadership and amid national anger over police killings of unarmed black men, is easing its limits on Tasers, which shoot electrified barbs. Over the last year, the Police Department has trained about 4,000 officers to use the devices, bringing the number of Taser-trained officers to nearly 10,000 on a force of about 36,000. In all, 1,710 Tasers are in circulation, nearly triple the number in 2015. A decade ago, 160 Tasers were in use.

The expansion has occurred as Taser has lobbied in New York to market its products, which include not only stun guns, but also body cameras for police officers. Since 2013, the company has spent more than $300,000 lobbying the Police Department and other city agencies, according to city records.