When Robert Hammonds and a friend, Brent Bredwell, finished filming a DJ show at Jazid in South Beach, it was around 3 a.m. on a Sunday in September. A few minutes later, after they jumped into a car and headed down Washington Avenue, a drunk-looking driver swerved across traffic and cut them off.

Hammonds leaned out the window and yelled "What the hell are you doing?" at the guy.

Next thing Hammonds and Bredwell knew, a beefy cop was pulling them over. Holding his Sig Sauer .40 caliber gun at his side, the officer angrily thrust his hand into the car through the driver-side window and waved his walkie-talkie.

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"Are you a fucking idiot?" the cop screamed. "Doing that in front of me? Asshole!"

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Hammonds, in the passenger seat, was discreetly filming the outburst. When reinforcements arrived to put Bredwell through sobriety tests, Hammonds kept taping and agitating. "Oh, it's martial law now!" he yelled.

Another officer gestured at Hammonds. "Take the camera," he said to a colleague. "It's evidence now. Take it."

On film, the frame shakes violently and Hammonds yells, "I do not release this camera!" But then an officer grabs it and shuts it off.

That confrontation, filmed in 2009, was the first of dozens that Hammonds and three friends caught on tape. They've paid dearly, spending thousands on legal fees and tickets, and sleeping multiple nights in county lockup. They've even seen their faces plastered on a warning flyer sent to departments around Miami-Dade County.

They're part of a simmering national fight between citizen journalists and police departments that believe subjects have no right to film them. The battle over whether cops can arrest you just for videotaping them is quickly becoming the most hotly contested corner of American civil liberties law.

"As more professionals and amateurs use equipment to record police activity, they're facing the ire of officers who just don't want to be recorded," says David Ardia, director of Harvard University's Citizen Media Law Project. "We need a clear answer from courts that this is legal, or else police officers' instincts will always be to snatch the camera."

It might seem like an open-and-shut argument — cops are public figures, after all, and they're operating in plain view on the street. But it isn't, at least in the dozen states, including Florida, that require both parties in any conversation to consent to audio recording.

Since video cameras also record voices, police argue, citizen journalists are breaking the law when they record cops without permission. Publishing cops' photos also jeapordizes their safety, says Detective Juan Sanchez, a spokesman for Miami Beach police.

Miami Police Department officers, meanwhile, say they only arrest camera-toting civilians like Hammonds when they harass cops and break the law. "When you go beyond filming to trying to piss off an officer, you're subject to arrest," says Delrish Moss, a department spokesman.

Police around the country agree with him. Last May, a man in Maryland named Anthony Graber posted a YouTube video made with a helmet camera. It showed a state trooper drawing a gun and threatening him during a traffic stop. A few days after the clip was posted, police raided Gruber's house and charged him with "illegal wiretapping."

In Massachusetts, courts have upheld several similar convictions, including one against Jeffrey Manzelli, a Cambridge sound engineer who recorded police at a public antiwar rally.

In South Florida, the American Civil Liberties Union (ACLU) sued the City of Boynton Beach this past June on behalf of a local woman named Sharron Tasha Ford. She had gone to a movie theater to pick up her son, a minor, whom police accused of trespassing. Ford said she had "a bad feeling" about the arrest, so she took a camera with her. When she refused to stop filming, she was arrested and charged under State Statute 934.03, the "two-party consent" recording law.

"It really is a perversion of this statute to try to apply it to filming or recording what public officials are doing in public," says Randall Marshall, legal director of ACLU Florida.

Hammonds and Bredwell didn't know about the legal infighting when they pulled out their camera on Washington Avenue 16 months ago. They just acted on instinct. "It's your responsibility as an American to monitor authority and to speak up when it's being abused," Hammonds says.

Hammonds is a 30-year-old Indianapolis native with shoulder-length hair, a goatee, and a perpetually aggrieved voice. He moved to Miami five years ago to study film at Miami International University. That's where he met Bredwell, a soft-spoken, six-foot three-inch filmmaker whose father is a cop in Fort Myers.

They never planned to become police agitators. But when Bredwell tried to retrieve his seized Sony camera the day after that first incident, he says Miami Beach police claimed not to have it in the evidence room.

A week later, the friends returned to police headquarters to try again. This time, they brought a full assortment of cameras and mics. They shot footage of the cops stonewalling Bredwell again. When officers noticed the cameras, they arrested Hammonds and charged him with obstruction of justice, loitering, and trespassing. He says an officer grabbed him by his hair in an interrogation room and then locked him in a sweltering van for two hours in 90-degree heat.

The day after Hammonds's arrest, Miami Beach police printed a flyer with mug shots of Hammonds, Bredwell, and a friend, Christian Torres. Headlined "FYI Officer Safety," it warned that the trio "were seen filming the Miami Beach Police Department" and were "extremely hostile" and "looking for a confrontation." Anyone who spotted them "should use extreme caution."