Reality shows routinely tail US police officers, filming them tangling with miscreants. Cops regularly film themselves from cameras mounted on cruiser dashboards – and now special hats. But if the state uses cameras for its own purposes and defense, why are so many citizens getting in trouble for pointing their cameras at the police?

The rise of security and red-light cameras coincides with ubiquitous photography, when nearly every American with a cellphone holds a reality-recording device in his or her pocket.

That democratization of photography is ratcheting up tensions between police, who sometimes feel beleaguered by citizen gotcha artists, and amateur photogs who claim a First Amendment right to record what’s happening in the public square.

“You can buy a digital camera the size of a stick of gum for 20 bucks,” says Radley Balko, a senior editor at Reason magazine and frequent critic of police power in the US. “As a result, we’re seeing all these videos popping up that show not only misconduct, but contradict what shows up in police reports after the fact.”

A growing list of police seizures cameras and destroyed pictures is testing the Constitution’s First Amendment protections. In a New Orleans case this week, two “copwatch” activists failed to win a civil conviction against New Orleans police officers who three years ago confiscated their cameras, erased footage, and arrested them for “crossing a police cordon” during the Bacchus Krewe Mardi Gras parade.

There’s more:

A famous YouTube clip shows a citizen videographer running away from a police officer trying to grab his camera after another officer allegedly shot a handcuffed man, Oscar Grant, in the back at a crowded public transit station in Oakland, Calif., on New Year’s Day 2009. (The officer claimed he thought his gun was a Taser, but citizen video evidence was used to bring murder charges.)

After a three-year legal battle over Miami photographer Carlos Miller’s arrest on a public street for refusing to stop taking pictures of several police officers, Mr. Miller saw all the charges dropped this week. (His compendium of such incidents can be seen here: carlosmiller.com)

The Boston Globe recently wrote a series about Massaschusetts police using an obscure wiretap law to confiscate crime-scene video recordings collected by passers-by.

Moreover, police often have the upper hand in court. The New Orleans jury, for example, found that the photographers brought their troubles on themselves.

Police have a legitimate right to object to filming that interferes with their duties. And “there's another reason cops are skittish,” explains one police officer commenting on a 2008 Popular Mechanics story titled Watching the Watchers. “As anyone who has ever seen a Michael Moore movie knows, creative editing and partial context can let you make film say whatever you want.”

Still, experts say it’s relatively easy for police officers to interpret obstruction laws too broadly.

“Photography can be a double-edged sword, depending on your perspective,” says Portland, Ore.-based attorney Bert Krages, author of “The Legal Handbook for Photographers.”

“One of the problems photographers do face is the vulnerability to being charged with things that they didn’t do, and where, absent images or independent witnesses, it then comes down to a citizen’s word against a police officer’s word.”

For many civil libertarians, police overreach is incontrovertible in almost all camera seizure and photographer arrest cases. “We have this thing called the Constitution, and the idea that you can’t film something that you can see is ludicrous,” says Marjorie Esman, executive director of the Louisiana ACLU. “The sad thing about these cases is it suggests that police don’t want people to know what they’re doing, which then implies that they’re doing something that they don’t want people to know that they’re doing.”

At least one state, Mississippi, is looking at whether First Amendment protections are strong enough to protect photographers in the video age. That debate needs to happen nationally, too, some law experts argue.

“Abuse of photographers is common, and difficult to remedy under current law,” writes University of Tennessee law professor Glenn Reynolds in an e-mail. “I believe that public officials performing their duties – including, but not limited to, law enforcement – should be subject to photography by citizens, and I would favor a federal civil rights law to that effect.”

More pragmatically, citizens do have recourse beyond the courts if they believe their First Amendment right to capture reality in the public sphere has been violated by an officer of the state.

“Complaining to a department’s internal affairs unit is a pretty effective tool in [educating] police departments better with respect to the rights of the public to take photographs,” says Mr. Krages. “And citizens can also get in touch with local or regional media. Newspapers have a deep interest in being able to photograph in public.”