Pareto efficiency

Relatedly, additional critique has been directed toward the assumed benefits of law and policy designed to increase allocative efficiency; when such assumptions are modeled on "first-best" (Pareto optimal) general-equilibrium conditions. Under the theory of the second best, for example, if the fulfillment of a subset of optimal conditions cannot be met under any circumstances, it is incorrect to conclude that the fulfillment of any subset of optimal conditions will necessarily result in an increase in allocative efficiency.[8]
Consequently, any expression of public policy whose purported purpose is an unambiguous increase in allocative efficiency (for example, consolidation of research and development costs through increased mergers and acquisitions resulting from a systematic relaxation of anti-trust laws) is, according to critics, fundamentally incorrect; as there is no general reason to conclude that an increase in allocative efficiency is more likely than a decrease.
Essentially, the "first-best" neoclassical analysis fails to properly account for various kinds of general-equilibrium feedback relationships that result from intrinsic Pareto imperfections.[8]
Another critique comes from the fact that there is no unique optimal result. Warren Samuels in his 2007 book, The Legal-Economic Nexus, argues, "efficiency in the Pareto sense cannot dispositively be applied to the definition and assignment of rights themselves, because efficiency requires an antecedent determination of the rights (23-4)."