The decision was reached on Wednesday after months of testimony including from the officer, Daniel Pantaleo, who used a chokehold to restrain Mr. Garner, who died after a confrontation. It came less than two weeks after a grand jury in Ferguson, Mo., declined to bring charges against a white officer who fatally shot an unarmed black teenager, Michael Brown…

The case exposed lapses in police tactics – chokeholds are banned by the Police Department’s own guidelines – and raised questions about the aggressive policing of minor offenses in a time of historically low crime. The officers, part of a plainclothes unit, suspected Mr. Garner of selling loose cigarettes on the street near the Staten Island Ferry Terminal, a complaint among local business owners.

Mr. Garner’s death hastened an effort to retrain all the department’s patrol officers and brought scrutiny on how officers who violate its rules are disciplined. Officer Pantaleo has been stripped of his gun and badge.