The deals that do get made are often perceived to be unfair by some of the parties, which then either back out of the initial deal (US, Canada on the Kyoto protocol) or prevent future deals (WTO Doha negotiations, and on a lighter note,
ice hockey player transfer negotiations between North America and Europe) from going through until the prior issues are resolved.
The other is the tension between the NHL and the International
Ice Hockey Federation, which brokers
transfer fees to European teams that lose
players to the NHL.