Good evening, a routine arrest goes very wrong, and a man seems to die at the hands of the police. The apparent chokehold now going across the country. And as the victim's family gathers, the issue is... See More
Good evening, a routine arrest goes very wrong, and a man seems to die at the hands of the police. The apparent chokehold now going across the country. And as the victim's family gathers, the issue is fraught with race and public safety. Reporter: This is the dramatic video that is triggering a wave of controversy. A violent confrontation on a new York City street that ends with one man, a black man, dead. And police accused of using excessive force and even racism. So just how much force is too much for police departments across the country? This happens every day in Detroit. In Chicago, in Los Angeles. You know, in Atlanta. This happens all across areas where there are large populations of people of color. And in rural areas. It is ugly, it is mean, we've seen this over and over and over. Reporter: It all unfolded in a matter of minutes. Two plain clothe police officers confronting Eric garner, for allegedly selling cigarettes, a misdemeanor. There is a tense standoff as he protests. Watch as the two officers move in and try to physically arrest him. Garner seems to resist, one of the officers puts his forearm around garner's neck and other officers join in, and within seconds the 350-pound man is down. From the ground, garner cries Ou out. I can't breathe, I can't breathe! Reporter: For several long minutes, garner lays on the ground, not moving. He was saying stop resisting, it was like, I'm not resisting, I can't breathe. And I already knew. Reporter: Paramedics arrive, one is seen on the videotape speaking to garner. Sir, answer the questions, okay? Reporter: But they appear to do something. Finally, garner is placed on a stretcher and taken by ambulance to a local hospital. About an hour later, the father of six children is pronounced dead. Itust snatched my heart right out of my chest, I'm an empty shell right now. Reporter: The cause of garner's death is still unknown. Autopsy results are expected in several weeks. But already, this case has taken on racial overtones. I do not believe that a white person would have been treated that way on Staten island by the police. Reporter: And prompted protests alleging police brutality. Something needs to be done about this. Nobody should have to die while being arrested. Mr. Garner's medical condition may have been the cause of it and not the action of the officers, but equally we have to look at the officer's action. Reporter: It is not just this case in this city. Police actions are coming under scrutiny all around the country, shining a spotlight on the controversial practice of chokeholds. A technique that most big city police departments now ban. A chokehold can cause death. A chokehold can cause suffocation. It is a dangerous maneuver. Reporter: This cell phone video captures a confrontation between the police and a Virginia woman. Petersburg police say that officers are trained to use the least amount of force. The woman was convicted of obstructing justice. And then there was this man in San Francisco, already in cuffs, who appears to be held in a chokehold by this officer. Police maintained it was not a chokehold but a carotid restraint, which is allowed. Back in New York, this video also under scrutiny showing the police appearing to forcibly restrain a man suspected of entering a subway station without paying. While one officer handcuffs the man, the other is seen putting his arm around the suspect's neck. Nypd says the incident is under investigation by the department's internal affairs bureau. Two officers were sent to the hospital. As for the garner case, some were asking was he really subjected to a chokehold. It is defined in the department's patrol guide that this would appear to have been a chokehold. Reporter: But former New York City cop tappano looked at the tape and he says it was not. I would be really hard pressed to call that a chokehold technique, that was more a restraint technique, submission technique. Reporter: Garner had been arrested 31 times. The police union says sometimes force is necessary at times when officers are required to make an arrest they must employ the use of force in order to get compliance. You resist arrest at your peril, whether you're right, black or whatever, police are going to knock you around if you resist. Reporter: Although still under investigation, the officer who put his arm around his neck, an eight-year veteran is reassigned to desk duty, pending the outcome. His badge taken away. It turns out Pantaleo was at issue for two other arrests, one for a wrongful arrest, one for a strip search, the four paramedics who responded to the scene and appeared to do nothing, they have been suspended without pay. What should be done when an emt arrives? Check for responsiveness, protect the cervical spine. Did you see evidence of that? If it happened it was not on the video. Reporter: The other police officers who took part in garner's arrest are also facing potential departmental disciplinary charges and some could even face criminal charges. In response to what happened on Staten island, a massive overhaul has just been ordered of the entire force. There will be re-training of every member of the police department. Reporter: All 35,000 cops to be re-trained in arrest procedures and the use of force. Tonight, a funeral service was held for Eric garner. We have every right to want revenge. We have every right to be disappointed with the system. Reporter: Hundreds of people turned out to protest. You think we are not going to fight this one? You can get ready for the long haul. We are not going to stop until we get justice. Reporter: And to mourn. Asking how what seemed to be a routine arrest ended up with a man dying. For "Nightline."
This transcript has been automatically generated and may not be 100% accurate.