Many years ago, while hiking with a friend, we came across a particular point in the trail which was rather dangerous. If one slipped, the fall would surely be fatal. What struck me most is the fact that there was a sign in/sign out sheets (which were in a green box with a plexiglass lid) at the beginning and end of this particular section of the trail. One was encouraged to print one's name, the date and time. The reason for the signing in and out was to know for a fact that hikers actually made it to the other end. If one did not sign in on the other side, Search and Rescue had a idea of where to look.
These sign in/sign out sheets were in mid trail and there were no sign in sign in sheets at the trailhead and no permits were required either.
My question is this: Are Sign in/Sign out sheets for dangerous passages while hiking a common practice? Are there any laws requiring this?