Protesters" Arrests During 2004 G.O.P. Convention Are Ruled Illegal A federal judge has ruled that the New York Police Department illegally arrested large numbers of demonstrators at a protest in Lower Manhattan during the 2004 Republican National Convention. But the judge upheld aspects of how the city had handled the protesters" arrests. Ruth Fremson/The New York Times A judge said the city did not have probable cause to arrest more than 200 antiwar demonstrators in Lower Manhattan on Aug. 31, 2004. The judge, Richard J. Sullivan of Federal District Court, said that the city had lacked the required probable cause because the police were unaware of whether each individual protester had broken the law. "An individual's participation in a lawbreaking group may, in appropriate circumstances, be strong circumstantial evidence of that individual's own illegal conduct," the judge wrote in a 32-page opinion. "But, no matter the circumstances," he added, "an arresting officer must believe that every individual arrested personally violated the law. Nothing short of such a finding can justify arrest. The Fourth Amendment does not recognize guilt by association. The ruling on the protest, which occurred on Fulton Street on Aug. 31, 2004, was a kind of test case examined by the judge of one group of plaintiffs among hundreds who filed false-arrest claims in the wake of the demonstrations, which rippled across the city during the convention and at times erupted into confrontations with the police. The ruling, dated Sunday, opens the door for the city to have to pay damages to the plaintiffs in the Fulton Street arrests. More than 200 were arrested during that protest, though not all have lawsuits pending. But the judge also rejected arguments that the city had violated the protesters" First Amendment rights by not treating their arrests as a lesser violation that would typically result in the issuance of a summons, and processing them instead through the courts, including detaining and fingerprinting them and taking them before a judge. The judge found that the no-summons policy passed constitutional muster because it was a response "to a threat derived from intelligence sources - namely, that demonstrators aimed to "shut down the City of New York and the R.N.C." through "continuous unlawful behavior," " and that they "would be undeterred by the issuance of summonses." He added that the policy "was in place only for the brief duration the threat existed." Both sides praised aspects of the ruling. Peter Farrell, a senior lawyer with the city's Law Department, said the demonstrations had made "an extraordinary security challenge." The ruling "validates two city policies the plaintiffs have spent almost five years exclusively litigating - to fingerprint arrestees and not to issue summonses," Mr. Farrell said. The court upheld these policies under the most exacting judicial scrutiny possible, finding them constitutional and warranted in light of the threats the city faced during the R.N.C. We are reviewing the remainder of the decision and considering our legal options in that regard. Christopher T. Dunn, a lawyer with the New York Civil Liberties Union, which represents some of the plaintiffs, said the judge had "emphatically rejected the city's claim that it could make mass arrests of protesters." "With this ruling," he added, "the time has come for the city to put this controversy behind it, to settle the rest of the convention cases, and to make sure that mass arrests never happen again here." Bob Curley, a lawyer from Philadelphia who was arrested near Fulton Street with his son, Neal, then 16, and held 16 hours, said that he thought the arrests in 2004 were meant to "discourage dissent" and felt vindicated by Judge Sullivan's decision. "I was pretty shocked when it happened," he said, describing the moment he was taken into custody. I said to my son this isn't the America I grew up in. Colin Moynihan contributed reporting.