In blunt, scolding language, a federal judge on Tuesday criticized the city’s conduct during legal negotiations aimed at diversifying the Fire Department, accusing the Bloomberg administration of shirking its responsibility for redressing discrimination and of exaggerating claims about threats to public safety during the dispute. The judge, Nicholas G. Garaufis, of Federal District Court in Brooklyn, also raised the possibility of imposing sanctions on New York City. In a 20-page decision, the judge, who had previously found that the city administered tests that discriminated against black and Hispanic firefighter candidates, ordered the city not to hire new firefighters. That permanent...