"The mayor as recently as a few days ago said one of her frustrations with trying to piece this together is that we can't seem to establish probable cause," her spokesman Kevin Harris said. "All we have from the police documents so far is that he made eye contact or he had a knife. From her years serving as a public defender, having a knife is not necessarily probable cause to chase or arrest someone. The information we have so far is clearly insufficient as well in establishing why he was pursued in the first place."
David Gray, a University of Maryland law professor who teaches criminal law and criminal procedure, said the Supreme Court has ruled that running away from police, by itself, is not justification for an arrest. Supreme Court Justice William Rehnquist wrote that refusing to cooperate with police "does not furnish the minimal level of objective justification needed for detention and seizure," the professor pointed out.