In Switzerland they had court cases about it. It even went further: a ticket Zrh-JFK costs 10000 Dollars in F Class, a ticket Cairo-Zrh-Jfk only 5000. A guy bought such a ticket and didnt fly Cairo-Zuerich and went to the airport in Zuerich to check in. They denied boarding and made him buy a new ticket for 10000 Dollars. He did it, took them to court and won, they had to refund him the seconfd ticket and pay costs. Court decided, that you are buying a ticket and its none of the airlines business if you fly all or not. Your ticket for Zrh-JFK is still valid, its like buying a package for 3 movies, if you didnt watch the first two, they cant deny the third. A few people since then did it and took them to court and all won. The airlines dont allow it and most people dont take them to court, but if you have the koiches you will win. Curious to know if there is such a court case in the USA