I know that when serving I must serve diagnally, but my opponents have a habit of catching the shuttle in midair when they think its going to land in the wrong section. It feels especially unfair when they catch it when it's very close to the line, but it seems to me that if they catch it at all, even if it's obviously going to be a fault, then it should be their fault.
I'm pretty sure that they shouldn't catch it, but I've been unable to prove it, and we don't have anyone around who knows for sure. I couldn't find a definitive answer in the rules, either, but that might be because I'm unfamiliar with the game. Does anyone know for sure?