The idea of the rule of law is arguably foundational; the actual legal system is not. More to the point, the rules that limit the government within the legal system are not foundational rules of society setting out limits on private interaction (they are, in some cases, foundational in that they express the ways in which government, including the legal system, is subordinated to the people rather than vice versa, but applying the rules of the legal system to private interaction inverts that foundational concept.)