Something to consider: suppose we do find life on Enceladus. What rights would these organisms — intelligent or otherwise — have, and how would we go about seeing that they are respected? It would be a tragedy indeed if we were discover life elsewhere in the solar system, only to extinguish it through carelessness.
We shall make a law that any life form killed on Enceladus is a brutal crime. We wouldn't interfere with it much. We could monitor if primitive, but have no right to guide its evolution.
My issue is that if there was some sort of patheogenic bacteria discovered, we then wouldn't be allowed to kill it, creating potential problems on earth.