On our most recent trip to San Francisco to visit our daughter United over booked the second leg of a flight we already had a ticket for and rather than have to ask people to take a bump and be forced to provide vouchers our itinerary was changed to a flight 9 hours later. Bear in mind this was a connecting flight and it was Chicago we were stuck in for a grand total of 11 hours. This after taking the red eye out of San Fran. How can they do this legally?