How to mute the camera shutter sound effect?

It used to be that I was able to use the lock switch on my iPhone to mute all alerts and sounds (with the exception of any music, video, etc.); and this included the camera's shutter noise. Then when I went to set the switch to the un-mute setting, I could get the camera's shutter noise back.

This was especially useful when I needed to inconspicuously take photographs.

It seems now, though—perhaps even as early as iOS 5.1, I can't recall—the camera noise goes off each time I take a photo, regardless of other mute settings.

And I've already toggling the Settings » Change with Buttons setting, it has no effect.

Is there some sort of hidden option I've lost track of to let me regain this functionality?

Solution 1:

Some countries (notably Japan and South Korea) have laws requiring camera phones to make audible shutter sounds.

I can't find a definitive reference for this (at least not one in English), but there are many second-hand references if you Google.