The city's defense in the case was weakened last year when federal appellate Justice Richard Posner ruled the arrests were unjustified because police allowed the massive demonstration to take place without a permit, but then decided to arrest people for participating without giving them a clear order that it was time to disperse.

Hundreds of people became trapped by police at Chicago and Michigan avenues. Confused demonstrators who said they just wanted to go home were instead arrested and held overnight. All of the arrest charges were later dismissed in court, Posner noted.

