Wants to remain in the U.S. for longer than 90 days, or envisions that they may wish to change their status (from tourism to student, etc.) once in the United States;
Wants to work or study in the United States, wants to come to the U.S. for other purposes not allowed on a visitor visa, or intends to immigrate to the U.S.;
Does not have a machine-readable passport (MRP) as of June 26, 2005.
Intends to travel by private aircraft or other non-signatory air or sea carriers to the U.S.;
Has been refused a visa or admission to the U.S. before, or did not comply with the conditions of previous VWP admissions (90 days or less stay for tourism or business, etc.); or
Has a criminal record or other condition making them ineligible for a visa (see Classes of Aliens Ineligible for Visas).