TSA officials declined to comment on the list of indicators, but said that no single indicator, taken by itself, is ever used to identify travelers as potentially high-risk passengers. Travelers must exhibit several indicators before behavior detection officers steer them to more thorough screening.

But a civil liberties organization said the list should not include behavior relating to the expression of opinions, even arrogant expressions of opinion.

“Expressing your contempt about airport procedures — that’s a First Amendment-protected right,” said Michael German, a former FBI agent who now works as legal counsel for the American Civil Liberties Union. “We all have the right to express our views, and particularly in a situation where the government is demanding the ability to search you.”