HERSHEY, Pa. -- Jeff Martin's legs collapsed under him, his muscles seized and he emitted an inhuman-sounding groan.

It's better than being shot, said Mr. Martin, a state trooper who yesterday volunteered to be jolted by an electronic immobilization device, better known by the brand name Taser.

Trooper Martin was back on his feet and feeling no ill effects moments after the 50,000-volt jolt that was part of a demonstration at a news conference yesterday.

Tasers were issued to 3,000 patrol officers in January and already have proven effective at subduing suspects without causing permanent harm, said police Commissioner Jeffrey B. Miller.

Officers discharged the Tasers 144 times in their first six months of use, he said. During that time, the use of mace and batons, which can cause permanent injury, declined.

"In some cases, there is no doubt our troopers would have been required to grapple with the individuals, strike them with batons or fire their service weapons to protect themselves or others," Col. Miller said. The Taser is an excellent alternative, he said.

The devices, which cost $899 each, were purchased with funds seized in drug arrests, Col. Miller said.

The devices shoot two darts attached to wires that carry a powerful electrical jolt that overrides the nervous system.

"It's overwhelming, completely incapacitating. I couldn't stand up, couldn't run, couldn't do anything," Trooper Martin said after the demonstration.

Those who oppose the use of electronic immobilization point to instances where suspects have died from them, and say that officers may overuse them.

Col. Miller said the only deaths reported occurred in people with a history of medical problems like heart disease, and that Taser alternatives, like batons and Mace, can occasionally be deadly, too. He said police have been well- trained to use the devices only when situations warrant.

He believes the devices already have given officers an alternative to deadly force in at least two incidents.

"Lives were saved. If troopers had to use sidearms, we would have had two dead suspects," Col. Miller said.

"The response from troopers in the field has been completely positive," he said. "One of the key reasons is that using Tasers means it's much less likely that an officer will become involved in a physical confrontation that could result in injuries to the suspect or the officer."