Is American Flag Clothing Illegal? Before you put on that American flag t-shirt for the 4th of July, you might want to know that wearing it is technically illegal because of a Federal Flag Code. That's according to the author Marc Leepson who wrote Flag: An American Biography. Leepson says, "Every item of apparel that they’re wearing that has an American flag on it: shirt, shorts, bikini, hat, technically is in violation of the flag code.” You shouldn't worry too much. Leepson said, “You have to look at it as a series of guidelines. There’s no flag police. No one’s going to get arrested.” Were you aware of the flag code? Will you think twice about wearing flag gear from now on?