Originally posted by Golgo13
There is no rule for it, though. They could very well be prepping for a JLA movie and a live action WW TV show as well. A JLA movie will happen, IMO. It's likely delayed, but there will be one eventually.
There's no rule written down, per se. But it's an understanding. Hollywood executives want you to come to the cinemas to watch what you can't see for free on TV. Hence why there won't be a live action Wonder Woman on TV and in the movies at the same time. They bent the rule somewhat with Smallville/Superman Returns, but it was a very different continuity with Clark not being Superman, there.
There are few examples of double dipping. Why I felt the X-Files movie was a cheat was because they wouldn't reveal or settle anything permanently, while the series was still ongoing. They did double dip during the animated days of Transformers in 1980's, but at least that movie signaled the beginning of a big new direction for the TV series that followed.