Augustine once said "posse pecarre, posse non pecarre" (able to sin, able not to sin) to describe the condition of Adam's free will, before he sinned. Which of course, is not the same as our current free will. That scholarstic notion is to better our understanding of predestination, free will, justice and original sin as a family of human beings - Adamites.
Murphy's Law is non-existent if its application to Adam's original state is in question, because Adam's state is a matter of obedience. Murphy's Law, if ever to be considered a law, could only be so in the context of observations, and not more than Schrödinger's cat.