The 21 protestors arrested during a Harlem rally against the NYPD stop-and-frisk policy had their day in court on Monday.
Two accepted offers to get their cases dismissed by staying out of trouble for six months.
The rest will be back in court on Tuesday, where the trial will continue with witness testimony.
The group on trial includes Princeton professor civil rights activist Cornell West.
During a news conference before Monday's court appearance, protestors said they were trying to stop a policy they think should be illegal.
"Stop and frisk don't stop the crime, stop and frisk is the crime," said Carl Dix of the Revolutionary Communist Party.
"We have a deep love for young brothers and sisters of all colors, but the disproportionate black and brown brothers who are targeted, we want to let them know that we care for them, we are concerned about them and we are part of the fight back against any attempt to treat them unjustly," West said.
In October, protestors formed a human chain outside the 28th police precinct stationhouse in Harlem.
Police said the demonstrators blocked the entrance and ignored orders to leave, but defense lawyers said there is reasonable doubt that any laws were broken.