Wired News: ID Rule Exists, But Can't Be Seen Internet entrepreneur Gilmore first challenged the constitutionality of requiring airlines to ask passengers to show identification in U.S. District Court in San Francisco in July 2002, but the government refused to tell that court whether the rule existed.

Gilmore argued that the rule is vague, since no one knows what kind of identification is adequate and the penalties are unknown. He said he opposes Americans being subjected to a secret law. The rule impinges upon the right to travel and leaves people open to unreasonable searches, he added.