Fresh protests have been held in New York and across the US for a second night over the death of Eric Garner, a black man held in an apparent chokehold by a white New York police officer.
Thousands of people took to the streets in New York and other cities, disrupting traffic and holding sit-ins.
The protests began on December 3, after a grand jury decided not to press charges over the death of Eric Garner.
Civil rights activists are pinning their hopes on a federal investigation into the case.
The mayor of New York, Bill de Blasio, said the city’s 22,000-strong police force would be retrained in how to better communicate and remain calm when making arrests, and they will be fitted with body cameras.
President Barack Obama welcomed Bill de Blasio’s commitment to act, adding: “Too many Americans feel deep unfairness when it comes to the gap between our professed ideals and how laws are applied on a day to day basis.”
America saw a wave of race-related unrest only last week over the decision not to indict another white police officer who had shot dead a young black man, Michael Brown, in Ferguson, Missouri.
UN human rights experts have expressed “legitimate concerns” over the decisions not to bring to trial the cases of both Michael Brown and Eric Garner.
On Thursday night in New York, protesters carried coffins across the Brooklyn Bridge and marched in several groups through Manhattan, carrying banners saying “Racism kills” and “This stops today”.
Police in riot gear told protesters staging sit-ins that they would face arrest if they did not move along. Police arrested more than 80 people in Wednesday’s protests, though the demonstrations have been largely peaceful.
Smaller-scale protests were held in cities including Chicago, Washington, Denver, and Boston. In Minneapolis, some protesters blocked traffic by marching or lying in the middle of a highway.
Activists have called for another march in Washington on December 13, followed by a summit on civil rights.
EricGarner, 43, was stopped on a street in New York on July 17 on suspicion of selling loose, untaxed cigarettes.
After a confrontation with police officer Daniel Pantaleo placed his arm round Eric Garner’s neck. Eric Garner, who had asthma, was wrestled to the ground and restrained by force.
On video of the incident, he can be heard repeatedly saying “I can’t breathe”. He became unresponsive and later died.
The city’s medical examiner’s office found in the summer that Eric Garner’s death was caused by “the compression of his chest and prone positioning during physical restraint by police”.
Police unions and Daniel Pantaleo’s lawyer have said that he used an accepted takedown maneuver on Eric Garner, rather than a chokehold, which is banned under New York City police regulations.
District attorney Daniel Donovan sought to defend the grand jury decision not to bring charges.
Daniel Pantaleo admitted hearing Eric Garner say “I can’t breathe” but said he had believed that once he got him down on the ground and put him on his side, he would be revived by paramedics.
The police officer also testified that he had tried in vain to talk Eric Garner into complying with police instructions – something not seen on the video.
“Let’s make this easy, you’ve been through this before,” the police officer is said to have told Eric Garner.
Attorney General Eric Holder promised “an independent, thorough, fair and expeditious” federal investigation into potential civil rights violations in the case.
A review of how to heal a “breakdown in trust” between police and communities is also under way.
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