[albeertoni]

Intercept legislation that applies to makers of non-interconnected (i.e., doesn't touch the PSTN) chat functions is extremely unlikely. I'm guessing whisper falls into that category.

I use Silent Circle myself, but I assume on Whisper you can't just type in a normal mobile number and have the chat message go to the right person. If you can, then those chats at least are subject to intercept, and maybe the other chats (whisper-whisper chats) are too. I don't remember how all those rules shake out/how courts have decided.