NBC with Brian Williams did a segment on this last night. They interviewed several 'officials' and the word was that if the traveler challenges a ruling, he/she is given SOME of the criteria they used to ban his travel, but not all.

Among the criteria - and I don't know the meaning and weight of each - are paying for someone else's travel, method of payment, one-way travel, seat placement, choice of meals... I don't know what all.