What about thinking caps?

Law.com article: An attorney does not have a constitutional right to wear jeans and a hat -- specifically, an Operation Desert Storm baseball cap -- while appearing in state court, a New York federal judge has ruled. Eastern District of New York Judge Nicholas G. Garaufis ruled that the court's dress code merely enforced "commonly shared mores of courtroom civility," and did not encroach upon the First and 14th amendments.