The suit argues that police disproportionately target minorities, often stopping them and frisking them without sufficient grounds.
The suit was filed by the American Civil Liberties Union of Pennsylvania and the law firm of Kairys, Rudovsky, Messing & Feinberg.
Among the named plaintiffs are an African-American, Georgetown-educated lawyer who the suit says has been stopped four times since 2008 in West Philadelphia "without probable cause or reasonable suspicion," and a Hispanic University of Pennsylvania ethnographer stopped four times this year in neighborhoods around Kensington without ever facing charges.
Another plaintiff is state Rep. Jewell Williams, who was arrested in 2009 near his North Philadelphia home after he witnessed what he described as overly aggressive police tactics and attempted to intercede.
The lawsuit says pedestrian stops have more than doubled since 2005, to 253,333 in 2009. Of those pedestrians stopped, 72 percent were African-American and only 8 percent led to arrests.
The plaintiffs are seeking class status and rulings to prevent the police from conducting pedestrian stops based on race or national origin. The suit also asks the court to order more police training, supervision and monitoring to ensure that
The controversial stop and frisk policy was instituted after Nutter took office in 2008 amid an increase in crime.
Outgoing Commissioner Sylvester Johnson predicted that the stop and frisk policy would be "a disaster." New Commissioner Charles H. Ramsey embraced the tactic and violent crime has dropped significantly in the past three years.