A few posters on this forum and others have reported being involuntarily bumped down from F/J to Y class. My question is, What or how must the airline recompensate you with for this, or does that all depend on the generosity of each individual airline? I saw someone on another thread got a 400 euro voucher, good for travel on that airline. But in a legal sense, since they did get you from point A to point B, what is your 'loss', aside from the difference in ticket price and comfort level?

If I were in the situation, I would want cash instead of a voucher. Maybe I don't want to continue to fly on an airline that overbooks business class.

To me the proper compensation is cash in the amount of more than the difference between what I paid and the lowest fare for the class I ended up in.

For all intents and purposes, a paid first passenger downgraded to coach should be flown free.

Disney hints:
http://members.aol.com/ajaynejr/disney.htm

Compensation will usually depend on whether the downgraded psgr. was flying on a paid ticket in First or Business (F or C) or was booked in the upgrade cabin using a complimentary upgrade. For the paid F or C psgr., many airlines are obligated to refund the difference in fare classes. Many will downgrade psgrs. using complimentary upgrades to avoid downgrading paid F or C. In the case of psgrs. using complimentary upgrades confirmed in F or C, the airline will offer a "downgrade" kit -- a package consisting of a confirmable upgrade for a future flight and some other amenities, such as drink or meal vouchers. Airlines may also offer to rebook the downgraded psgr. on an alternate flight or connections, should upgraded space be available and the psgr. agrees to the rebooking.