For the legally-challenged such as myself, what is the importance of common law here?
Common law is the foundation of law in most of the states in the United States.
It is a law based more on principles than on any specific statutes or regulations.
Many, if not most of the rights spelled out in the Bill of Rights are common law rights (the rights of a FREE MAN, a Freeman).
These are the things that can be traced back to the time when a bunch of Lords in England sued for peace and got the king to sign the Great Charter. The Magna Carta.