It is a commonplace the misinterpretation of the defence of a political system whose decisions are based on the principles of the spontaneous order as the promotion of a spontaneous legal system. A spontaneous order is not a spontaneous legal system. The former is a complex phenomenon made of an abstract structure of heterogeneous elements that allows us to make pattern predictions about the general behaviour of the set of the said elements. The later is a set of rules of conduct grown out of custom in a given society that is enforced by the State or by retaliation.
A spontaneous legal system concerns the legality of a particular action and its subsequent legal effects (for example, the legality of the retaliation); whereas the spontaneous order is related to the legitimacy of the political order that enforces the legal system (be it spontaneous or not). A government is legitimate as long as it fulfils the expectancies generated by the spontaneous order, which is achieved majorly by acting based on principles than based on expediency.
The main source of principles for the government to base its decisions on is the given spontaneous order. This principles may consist in the recognition of a given spontaneous legal system -as the lex mercatoria- or they may consist in the defence of the equality before the law, in which case the legislative activity may be required in some society. Since the spontaneous order is a concept related to the problem of legitimacy of a political system, it has no place in the legal theory. Or maybe it has a role to play in the case of the “state of exception”. After all, Friedrich Hayek renamed the Spontaneous Order as the “Abstract” Order, in a sort of counterpoint to Carl Schmitt’s Concrete Order.