Brad Lander, who wants to be the mayor of New York City, was arrested by the police at a court. He was watching immigration cases there. When the police tried to take a man, Lander held his arm and asked to see a paper from the court. The police then arrested Lander. After he was set free, Lander said he was trying to protest against the government's immigration rules in a peaceful way. Other politicians from his party said the arrest was not right.