It does say in the laws that the receiver must not be unsighted; in a formal setting, an umpire will interpret this as implying they must have a clear view of the shuttle during service.
No, what it says is 9.7 In doubles, the partners may take up any positions which do not unsight the opposing server or receiver. That's nothing to do with what the server does with the shuttle. Unless it's another law to which you refer...
*checks* Nope, you're right Presumably there has never been the need to add this rule, since serving with the shuttle concealed is very awkward and doesn't gain an advantage.
Hi Guys... I happen to try this behind-the-back, below-the-butt serve. Definitely the shuttle can be seen (just a slight drop from my left hand) and all of the rules are observed. It is purely an element of surprise serve but I don't think I would dare to use it during tournament even though I could do it quite accurately to within a shuttle height off the tape as my racket would be in an awkward position.
