Comment by ehasbrouck

This is not true, in at least 2 respects: (1) a common carrier has a legal duty not just to sell a ticket but to provide transportation according to the tariff, and (2) this means an airline can't order a passenger not to board, or order them off the plane, unless they have violated some terms of the tariff. Some airlines have tried to create their own no-fly lists, but without opening up another area of discussion these have no more basis in law than the government's no-fly list, and have never (so far as I know) been reviewed by courts.