Originally Posted by J-FLyer

"This has nothing to do with capitalism, but with simple contract law. An interesting suit would be by a passenger who was forced to make do with half-a-seat."

How can you be forced? Just try to explain the problem to the authorities. If they can't accomodate you with a seat change, and won't follow standard over-sold protocol, just get off the plane. You will recoup the consequential damages (new ticket cost) in the law suit for breach of contract. In fact, the airline will likely settle fore more.