A sixth-grade student in Lakeland, Fla., who had refused to participate in the Pledge of Allegiance throughout the school year, was arrested this month after he had a dispute with a substitute teacher who confronted him about why he was not reciting it, the police said.

The case against the boy, 11, who was arrested on Feb. 4, has drawn outrage from the American Civil Liberties Union and his mother, who have criticized the misdemeanor charges against him as an overreaction by Polk County Public Schools and the middle school resource officer who arrested him. The boy told the teacher that he did not stand because he believes the pledge represents racism.

On Tuesday, Brian Haas, the state attorney for the 10th Judicial Circuit in Florida, which handles cases in Lakeland, said that his office would not prosecute the boy despite statements by the police that he had made threats after disrupting class. “The case is closed,” Mr. Haas said.

However, earlier on Tuesday, a lawyer for the boy’s family suggested that the case had not been resolved because the boy’s mother, Dhakira Talbot, declined an offer from prosecutors on Monday to drop the case if the boy completed a so-called diversion program, which could include a fine and community service.