They have "Law of Unintended Consequences" on this list which describes the same phenomena.

I always liked the fence story better though.

Found your comment by searching to see if anyone mentioned it. Really key in legacy systems.

This is one of my biggest principles too, "think before you do."

the corollary of Chesterton's Fence is also valuable: don't go putting up unnecessary fences, because others won't be able to take them down