(FORTUNE Magazine) – Don't laugh: though it sounds like something out of a Farrelly brothers movie, the latest technological breakthrough in law enforcement is in fact a stun gun.

Stun guns got a bad rap in the '70s (they were known for being underpowered and ineffective, and most required direct contact--not great when the person you're trying to stun has a knife). But over the past few years the technology has improved dramatically, and now a little company in Scottsdale called Taser International is reaping the benefits.

Taser's guns shoot two small darts up to 21 feet; the darts are attached to wires that send electrical pulses into a victim's nervous system. Taser CEO Rick Smith says the electrical frequency has been fine-tuned so that only muscle tissue is affected, and the heart and other organs aren't damaged. Smith has been shot six times in tests and demonstrations, and says the sensation is akin to a hard rap on the funny bone and five seconds with no control over your muscles.

For cops the benefit is a dramatic reduction in injuries to criminals and officers. The Orange County (Florida) Sheriff's Office reports a 72% reduction in the use of chemical and physical force against suspects since introducing Tasers in 2000. Cincinnati police chief Thomas H. Streicher Jr. says the newest Taser is the "only instrument to revolutionize an aspect of policing in the past 35 years," likening it to the development of portable police-band radios in the 1960s and '70s.

Taser doubled its law-enforcement business last year and now supplies 24% of U.S. law-enforcement agencies. Net income grew by more than 2,000% in 2003, and frenzied investors have sent the stock rising 3,000% in the past 12 months.

More good news for civilians hankering for self-protection: The company is introducing a $1,000 personal-defense version, the Taser X26C, in July. Kazam! --Kate Bonamici