Randy E. Barnett
The liberal fusion of justice and the rule of law of the sort defended here has not been without its critics. Some criticize it for erecting a barrier to the realization of certain desired forms of social life. Others criticize it for being inadequate to ensure the sort of social life or "community" we need or desire, or a just distribution of resources, or the retributive punishment of criminals. According to the first of these criticisms, the liberal fusion of justice and the rule of law prevents the achievement of some visions of the good and is therefore "too much"; according to the second it is "too little" to guarantee the achievement of some vision of the good or a different conception of justice. While the analysis presented in the previous chapters does not address every particular of these charges, it does cast some new light on these perennial controversies.
Liberalism distinguishes between "the just" and "the good." The just is defined by the liberal fusion of justice and the rule of law and is enforceable. The good - whether good conduct or a good society-is defined by other kinds of moral analysis and is unenforceable. The distinction between the just and the good also corresponds to the distinction described in Chapter 1 between natural rights which define justice and injustice, and the natural law which defines virtue or good conduct and vice or bad conduct.
To distinguish the just from the good, natural rights theorists sometimes separated "perfect" rights and duties that are enforceable from "imperfect" rights and duties which are not.
[S]ome things are due us by a perfect, others by a imperfect right. When what is due us in the former score is not voluntarily given, it is the right of those in enjoyment of natural liberty to resort to violence and war in forcing another to furnish it, or, if we live within the same state, an action against him at law is allowed; but what is due on the latter score cannot be claimed by war or extorted by the threat of the law ... But the reason why some things are due us perfectly and others imperfectly, is because among those who live in a state of mutual natural law there is a diversity of the rules of this law, some of which conduce to the mere existence of society, others to an improved existence. And since it is less necessary that the latter be observed towards another than the former, it is, therefore reasonable that the former be exacted more rigorously than the latter, for it is foolish to prescribe a medicine far more troublesome and dangerous than the disease. 
To appreciate Pufendorf's claim that the "medicine" of
enforcement is "far more troublesome and dangerous than the disease,"
recall the discussion in Chapter 10 of rights as a "necessary evil." There
I emphasized that because rights legitimate the use of force, the more
rights we recognize the more violence we legitimate. Every exercise
of violence imposes serious enforcement costs on the innocent and every
erroneous and unjust use of violence threatens to induce resentment, bitterness,
and the desire on the part of those against whom violence is used to rectify
this injustice by responding violently, thereby setting off a cascade
of violence. In considering whether liberalism does too much or too little
in pursuing the good, as opposed to the just, or whether the concept of
justice should be expanded beyond the rights needed to handle the problems
of knowledge, interest, or power, it is important to keep this in mind.