TAMERA MEDLEY begged the police officer to stop slamming her head - over and over - into the hood of a police cruiser.

Thinking they were helping, passers-by Shakir Riley and Melissa Hurling both turned their cellphone video cameras toward the melee that had erupted on Jefferson Street in Wynnefield, they said.

But then the cops turned on them.

Riley had started to walk away when at least five baton-wielding cops followed him, he said, and they beat him, poured a soda on his face and stomped on his phone, destroying the video he had just taken.

Meanwhile, two officers approached Hurling, urged her to leave and, after exchanging a few words, slammed her against a police cruiser, Hurling said. They pulled her by her hair before tossing her into the back of a cop car, she said.

Although it's legal to record Philadelphia police performing official duties in public, all three were charged with disorderly conduct and related offenses, and officers destroyed Hurling and Riley's cellphones, erasing any record of Medley's violent arrest, the pair said.

Charges against Hurling and Riley were dismissed, but Medley was found guilty last month of disorderly conduct, resisting arrest, harassment and related offenses. She was fined $500 but has filed an appeal.

Echoes of the incident, which was corroborated by a half-dozen witnesses, have been reverberating nationwide in recent years as the combination of cellphone video and police officers has simmered into what is an increasingly explosive formula. A growing number of bystanders have been misled, arrested or worse for using their cellphones to record what they perceive as excessive force by cops making arrests, watchdogs say.

"I grew up in the neighborhood and I saw stuff go down but it never happened to me," Riley said recently, adding that he did nothing wrong. "They stomped my phone and said it was a federal offense."

'Relevant for integrity'

The issue is gaining national attention. The American Civil Liberties Union has civil lawsuits pending in Washington, D.C., Florida, Illinois and Maryland. Last week, a federal appeals court in Boston ruled that police had violated the First Amendment rights of a lawyer who was arrested after filming cops arrest a teenager.

Suits have been settled in Pennsylvania, and this year, the ACLU plans to file a lawsuit on behalf of several Philadelphians.

"It is clear in our experience that police react badly to being caught on tape, on video," said Mary Catherine Roper, staff attorney at the ACLU of Pennsylvania's Philadelphia Office. "This is an opportunity for everybody to document what the police are doing." Roper wouldn't say who will be included in the Philly lawsuit.

Evan Hughes, a lawyer representing Medley, Hurling and Riley who plans to file a civil suit after Medley's case is resolved, said that the video could have aided in the investigation.

"When an officer uses excessive force, they will accuse the suspect of assaulting them," Hughes said. "It takes a video to prove it was in fact the police officer."

Some police officials argue that people who attempt to record often impede an investigation.

"It's a recipe for disaster. We have people getting in the way of an investigation," said John McNesby, president of the Fraternal Order of Police. "They have their right to tape, [but people have] to be mindful that officers are out there conducting an investigation. The safety of the officer is pertinent."

And police officials caution that any video shows only part of the story, usually leaving out what led up to a contentious arrest, as was the case when a news helicopter filmed the violent arrest of three suspects in Feltonville in 2008.

"With the video footage law enforcement receive at times, they don't get the full, complete incident," said police spokesman Lt. Ray Evers. "Things happen before and after. With video, it is what it is and the chips fall where they may."

For instance, in the Wynnefield incident, which occurred last summer, Medley was leaving a corner store when she stumbled upon a crowd watching police arrest a neighbor.

Medley, 27, said that an officer yelled at her to cross the street to get away from the scene, then charged toward her. The officer said in court last month that he restrained Medley because she was "loud and boisterous," wouldn't obey his orders and was resisting arrest. (Police said that Hurling and Riley were arrested because they didn't obey orders to leave the area.)

Even if Riley and Hurling's videos hadn't been destroyed, though, their videos wouldn't have shown whose version of the story was true.

In other states, and in one case in Pittsburgh, authorities have used laws banning wiretapping as justification for filing charges against those who film police, but experts say those laws weren't intended to apply to a public servant performing job duties in a public place.

"Visual recording is a permanent part of our way of life. It's an accountability measure, so we know who does what," said Samuel Walker, author of several books on policing, criminal-justice policy and civil liberties. "When talking about public officials in a public space, that's relevant for integrity of the justice system."

Philadelphians who find themselves corralled into this issue have mostly been charged with disorderly conduct, but even that goes too far if the only offense is filming police.

"We always try to make officers aware of the fact that they're being filmed by someone or something," said Deputy Police Commissioner Richard Ross. "You should always assume in today's climate, even as a private citizen, that your actions are being captured. Provided you don't put yourself in harm's way, we don't have the right to stop you."

'It was surreal'

Despite the department's training, Philly cops have clashed with several people trying to record them and are sometimes unaware of what the rules are.

In the Wynnefield incident, residents told the Daily News that cops went after people who were recording and confiscated or broke their cellphones. A neighbor found Hurling's phone bent, with its memory card missing.

"They're supposed to be public servants, not abusers of the people they serve," said Berusche Jackson, who witnessed the melee and said he saw a cop stomp Riley's phone. "It was surreal."

In another case last month, police allegedly began beating Darrell Holloway, who is legally blind, with flashlights and batons during a narcotics investigation on a West Philly street. There wasn't much his cousin Jamal Holloway could do but record the incident on his phone.

Jamal, 33, said that when officers spotted him filming, he was detained and taken to a police station at 55th and Pine streets. Before he was brought inside, an officer told him to delete the video.

"One female cop told me to delete the stuff and then I can walk," Jamal recalled, adding that the cop said she would confiscate his phone. "I was there close up. I can't believe it happened like - they beating my cousin like that and he's in the situation he's in."

Jamal said he opted to erase the footage.

"As part of the investigation, we're not aware of anyone brought to the station besides those that were charged," said Lt. John Walker of Southwest Detectives.

Then in July, Zanberle Sheppard, 24, said neighbors told her that police were beating her handcuffed boyfriend, Tayvon Eure, in an alley behind their home on 65th Street near Chester.

Sheppard said she peered out her back window and began to film the arrest. After officers saw her, she said, they banged on her neighbor's door. Sheppard ran outside and around to the alley with her cellphone, she said, and that's when a cop told other officers to grab her phone.

She claims that when she pulled away from the cops, one officer grabbed her by her hair and she dropped her phone. Neighbor Robin Artis, 17, said she saw a cop punch Sheppard in the face and stomp her. Sheppard had a black eye and a bruised lip.

The next time she saw her phone was when the cop who allegedly beat her boyfriend came into the police station where Sheppard was and threw it at her, she said. The back of her phone was broken, the battery was missing and the video was gone.

Evers said Sheppard was told to "back away from the patrol car that contained her boyfriend, who was arrested for narcotics. The defendant pulled away from the officer and actively resisted." Evers said Sheppard was arrested after a brief struggle.

Sheppard, a mother of three who has no criminal record, was charged with disorderly conduct.

"I never get in trouble with the law," Sheppard said. "I didn't do nothing. I was just recording."