It's recited in schools across the US every day by students standing stiffly with their hands over their hearts.
"I pledge allegiance to the flag of the United States of America and to the Republic for which it stands, one nation under God, indivisible, with liberty and justice for all."
The Pledge of Allegiance has been a part of American life since 1892, when it first appeared in a magazine to commemorate the 400th anniversary of the voyage of Christoper Columbus to America.
But the patriotic oath, despite its ubiquity, is not a legal requirement. Students don't have to recite it.
Why? It violates the First Amendment, which protects free speech.
The pledge made headlines this week after a sixth-grade student in Florida told a substitute teacher he would not stand for the pledge because he believed the American flag symbolized discrimination against blacks. ( He was arrested , although police said it was because he started a disturbance at the school, not because he wouldn't participate in the pledge.)
The substitute teacher didn't know that students can't be compelled to participate in the pledge, the school district said. That's been true since 1943, when the Supreme Court ruled in the case of West Virginia State Board of Education v. Barnette that students couldn't be forced to salute the US flag or say the pledge because doing so would violate their First Amendment rights.
"If there is any fixed star in our constitutional constellation, it is that no official, high or petty, can prescribe what shall be orthodox in politics, nationalism, religion, or other matters of opinion, or force citizens to confess by word or act their faith therein," Justice Robert Jackson wrote in the majority opinion . "If there are any circumstances which permit an exception, they do not now occur to us."
The case ended up with the high court after West Virginia's state Board of Education passed a resolution in 1942 requiring students and teachers to salute the flag. A group of Jehovah's Witnesses sued, saying the requirement went against their religious beliefs.
Legal challenges involving the Pledge of Allegiance continue to pop up from time to time, with more recent cases centering on humanists or religious freedom groups trying to eliminate the phrase "under God" from the pledge, according to the National Constitution Center . That phrase wasn't added to the pledge until 1954, during the Cold War, when members of Congress reportedly wanted to emphasize differences between the US and the atheistic Soviet Union.