Robinson died earlier this month after being hit by a squad car as police chased him in Canarsie, Brooklyn for allegedly stealing paving stones.
His family says he was unarmed, and they are demanding an investigation as to why police ran him over.
They want to know why the officer who hit him has not been punished.
"The officer that hit this young man rushed to judgment," said Sharpton.
"We deserve justice because my son did not deserve to die like that," said the victim's mother, Laverne Dobbinson.
The family is planning to pursue a wrongful death suit.
The N-Y-P-D has said it is conducting an internal investigation into the officer's role in Robinson's death.
The 27-year old was in a coma for a week before he died.
His funeral was Friday evening.
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