This is the question considered in "Airport ID checks legally enforced?" which discusses a court case brought by John Gilmore of the Electronic Frontier Foundation. The government admits that there is no public law requiring identification. But the Constitution does not necessarily guarantee any right to travel anonymously. So is the requirement legal? Is it a violation of privacy?
- Secret ID Law to Get Hearing (Wired)
- Privacy advocate asks court to expand case about showing ID (San Jose Mercury News)
- Millionaire headed to court in fight over ID regulations (Pittsburgh Post Gazette)