A federal judge yesterday issued a decision barring police use of four-sided pens to contain protesters at the Republican National Convention in New York City. The ruling also limits police searches of protesters, though it does not restrict the use of metal detectors. Judge Robert Sweet wrote that he aimed to strike a balance that would “encourage free expression in a secure society.” The New York Civil Liberties Union brought the suit against the City of New York citing excessive use of force and restrictive crowd control measures at recent mass demonstrations.