Smile. You're on candid cop camera.

In that most representative of public assemblies - the bustling House chamber of the New Hampshire State House - there's an old rebellious notion: In matters of personal responsibility, don't always err on the side of safety. After all, it's the only state not to require that adults wear seat belts.

So when a bill came up in early April to consider allowing robotic traffic cameras at the busiest crossroads, mocking laughter from the gallery preceded the measure's demise.

"The idea that we were going to be photographed [by the government] was anathema to most of us," says Neal Kurk, a Republican from Weare, N.H.

New Hampshire's famously skeptical lawmakers aren't alone in their queasiness. Despite continued growth in the number of "red light cameras," an emboldened opposition has cropped up in state legislatures from Hawaii to Virginia.

Even with their impact on safety still up for debate, the ticketing shutterbugs can be attractive "revenue generators" for local governments and the private companies that make, sell, and maintain them. And though constitutionally sound, the cameras raise privacy concerns among Americans who are already wary of the government riding shotgun.

"The opposition to red-light cameras isn't that they're not useful, but the problem is they're too useful," says Neil Richards, a constitutional law professor at Washington University in St. Louis. "This is part of a trend where [lawmakers] are seeing there's a political advantage to not living in a police state."

From Garland, Tex., to New York City, the number of cameras is still on the rise, with some 140 communities seeing 40 percent more of them in the past two years. In many places, they're a popular way to reduce certain kinds of accidents - mostly side-impact or T-bone collisions - and discourage red-light runners, particularly on packed urban crossroads. More than 300,000 red-light violations were issued in New York in 2003, and traffic deaths dropped in the city from 701 in 1990 to 344 13 years later.

Here in Raleigh, by some measures, total traffic accidents have gone down 25 percent at some half-dozen intersections. Urban lawmakers, backed by numerous police chiefs, say red-light running has become a pandemic - and cameras are a legitimate antidote.

"Numerous courts have ruled that there's no expectation of personal privacy upon a public road," says Chris Galm, spokesman for a camera-industry group called National Campaign to Stop Red Light Running. "The point is to modify their driving habits."

Yet despite the cameras' impact, a growing number of lawmakers say the devices put states on the wrong road. In the past few weeks, New Hampshire, Virginia, and Indiana have all moved to ban or limit their use, following failed attempts to introduce the cameras to Hawaii, Louisiana, Michigan, Missouri, and West Virginia last year. Even in New York, the city council has capped the number of cameras at 50. Critics cite privacy concerns, worries about a "money grab" by private companies, and studies showing that while T-bone accidents are reduced, the numbers of rear-end accidents tend to rise as motorists slam on their brakes to avoid tickets.

In Virginia, where cameras have been clicking for 10 years, a sunset clause in the original bill meant the pilot program came back up for a vote this year. The bill was not renewed, and dozens of cameras will be shut down July 1.

Now, as part of the same backlash, eight states are moving to bar insurance companies from peeking at data recorders, or "black boxes," that store driving patterns and are carried in some 30 million American cars.

In Baltimore, a $10 million class-action lawsuit charges that the city reduced the length of yellow lights to boost revenue from red-light runners. A North Carolina court ruled that it's illegal for private companies to make money off of traffic scofflaws. In Greensboro, that means the school district should have received all proceeds from traffic tickets. Now, the city owes its school district millions. While appeals mount, the city has turned off its cameras.

"The question is the extent to which the government is allowed to use this technology against people," says Eric Skrum, a spokesman for the National Motorists Association (NMA) in Waunakee, Wisc. "All these things start off in the guise of safety, but in reality have the potential of being used against you as a revenue generator."

Indeed, the NMA says the cameras put an undue burden on motorists' presumed guilt rather than common-sense solutions, such as increasing the duration of yellow lights. The organization has put out a $10,000 reward for communities that solve red-light problems through engineering rather than enforcement.

Camped out at the corner of Wilmington and Morgan in Raleigh, where a camera monitors the traffic flow, Civil War re-enactor Michael Hicks is on hand to sack the Capitol on the anniversary of Raleigh's fall. He ponders the 21st century, too. "If there's a ticket, there ought to be a cop behind it," he says.

But his comrade Robert Conner sees a greater social good in the camera. "I don't really see it as a privacy issue, since it's a public street," he says. "They also help keep insurance rates down - for everybody."