A stealth experiment using night vision gear to catch drivers violating Maryland's seat belt law was shut down yesterday after Gov. Robert L. Ehrlich Jr. declared the tactics "government intrusion into private decision making."

Last week, as part of a national campaign to encourage drivers to wear seat belts, state troopers in Montgomery County borrowed gear from the Maryland National Guard. During a three-hour effort on Rockville Pike, the state police identified 111 unbuckled passengers or drivers, fined $25 each.

The operation, covered by local TV stations, set off complaints on talk radio the next day. It also caught the governor's attention.

"It caused a lot of anger to me when I found out about it," Ehrlich (R) said Saturday on WBAL-AM radio. "There is an issue with government intrusion into private decision making."

Yesterday, he directed the Maryland State Police to stop using the equipment for seat belt enforcement, although troopers said the program had ended last week.

The governor has opposed other recent efforts to clamp down on traffic violations for similar reasons. Ehrlich vetoed legislation two years ago to allow radar-activated speed cameras throughout the state and rejected a narrower bill last month that would have let Montgomery County install the cameras near schools and in residential neighborhoods.

"The governor has strong views on Big Brother tactics," spokeswoman Shareese N. DeLeaver said. "The governor feels there is an appropriate use of the night vision goggles, however, he does not believe seat belt enforcement rises to that level."

State Sen. Ida G. Ruben (D-Montgomery), who sponsored the seat belt law in 1997, called the governor's decision to discontinue to the use of the night vision devices "absolutely wrong."

"The police are trying to prevent accidents from happening where someone could be killed, rather than saved," she said.

Deploying the night vision equipment, she said, is the equivalent of setting a speed trap. "They are hiding on side streets to prevent people from speeding," Ruben said. "What's the difference?"

A spokesman for Col. Thomas E. Hutchins, the state police superintendent, who is an appointee of the governor, said the equipment had been returned to the National Guard.

"It was tried that one time and won't be tried again,'' state police spokesman Greg Shipley said.

The use of the night vision equipment -- a six- to eight-inch hand-held device with a single eyepiece -- reignited debate about the state's seat belt law. In Maryland last year, 49 percent of the 643 people who died in traffic collisions were not wearing a seat belt.

Gregory Massoni, Ehrlich's press secretary, said the governor always wears a seat belt and encourages other drivers to do so. But he said Ehrlich opposes the state law that allows police to ticket unbuckled drivers absent another traffic violation.

Maryland is one of 21 states, plus the District, that have what is known as "primary enforcement" of seat belt laws.

The tactics inspired feverish protest during all three hours of the Chip Franklin talk show on WBAL radio Thursday. Franklin said about two-thirds of his callers were livid about what they considered overzealous enforcement of the state's seat belt law. "Callers were frustrated to live in a state that treats them like they are 7 years old," he said. "It was just a scare tactic that went awry. It would be funny if it weren't so Orwellian."

The state police were assisted by the Montgomery County police. Lt. Eric Burnett, Montgomery police director of media services, was more circumspect. "I don't want to get into whether it's right or wrong,'' he said.

But he said the department has no plans to use the night vision gear it purchased for undercover investigations to track down seat belt violators.

Staff writer Matthew Mosk contributed to this report.