This is the tradition of common law, and is not unique to the US. The job of the courts is to discover law. Even in the case where a sovereign dictates a law (o

This is the tradition of common law, and is not unique to the US. The job of the courts is to discover law. Even in the case where a sovereign dictates a law (older form, in monarchies) or a legislative body writes a law (modern form, in many republics and democracies), it is the duty of the courts to interpret these laws, both in the written law's specific verbiage, and its application in the context of other legal decisions. It is effectively impossible to legislate every aspect of society. One solution is to empower the judiciary to create/discover law. I am not making a qualitative judgment here, merely observing that this is not an instance of malfeasance or overreach in any way.