Judges discover common law, the same way the mathematician discovers the value of pi. A seemingly obscure distinction, but essential in understanding the base theoretical underpinnings of freepers. Law is not created by judges, just discovered.
This is what most call "natural law" theory, and when freepers appeal to "common law," this is generally what they mean. It is a popular school of thought around the time of American independence.
The problem with all of this is that the underlying assumption, that all people share the an innate concept of right and wrong is true to a point about obvious matters and is workable in rural culturally homogeneous societies circa 1750 but breaks down as societies become more complex and diverse. While "don't kill for no reason" is an "obvious" moral rule that to some level can be seen as innate, it boggles the mind how one could "discover" traffic laws like speed limits in cities. (note the general freeper hostility to traffic codes and regulatory laws)
Likewise, as societies become diverse, "common sense" things for someone in England like "women should not go topless in public" is nothing near common sense for an African native. for whom going topless is a traditional indication of being unmarried.
For most people it becomes clear that some level of legal positivism, that the law is what we say it is rather than some innate "true law," is necessary for society to function. Freepers are the extreme end of refusing to do this and then building wildly strange analytical frameworks to fit their prejudices and beliefs into the "natural law" framework.