Originally Posted by colpuck

That's pretty muddled. The Plaintiff always carries the burden of proof, if he meets it then the defendant/respondent can prove an affirmative defense.

You are correct that people are entitled to the benefit of their bargain. This isn't a breech of K issue like the million miler. This is a question of contract construction.

If it's a valid contract as issued then the OP is entitled to his economy seat and that's that.

If the OP can prove there is mutual mistake, the he is entitled to have contract rescinded. In opposition UA's argument is that OP is consciously ignorant of the rules he was provided and therefore OP needs to bare the risk of any mistakes.

If the OP wants more than that and wants UA to pay some sort of damages then the OP has to prove by the civil standard that UA fraudulently induced him into the contract and stood to benefit from that inducement. UA's argument is still going that OP was consciously ignorant of the contract when he signed.