DHS regulations require that prior to ANY training event, whether part 141, 121, 135, or 63(?), the identity of the trainee and their legality to recieve training has to be determined through either a passport and or green card or other accepted means. (See Hoserpilot's post. http://www.airlinepilotforums.com/801165-post35769.html ) Passports are issued by the Federal Govt whereas an airline ID is not. The regulation goes far beyond just airlines.