In this entry, we first explain the Neo Brandeisian or New Brandeisian school of thought. We link the New Brandeisian School with its namesake, Louis Brandeis, detailing his impact on antitrust in its historical context. The New Brandeisians gain their name in part to the influence of the original Brandeisians who shaped antitrust policy in the period that we call the “New Deal Consensus,” which lasted up to the takeover by the neoliberal revolution and the rise of the Chicago School in the late 1970s. We also explain how the takeover was fueled by the economic crisis of the 1970s and by the backlash to the crisis of that decade by big business and the wealthy. The Chicago School of antitrust posited both a positive theory of antitrust and a normative theory called the Consumer Welfare Standard. We explain what the consumer welfare theory is and explain its origins in the work of Alfred Marshall. We next explain the New Brandeis critique of the Consumer Welfare Standard, which focuses on its negative consequences for antitrust jurisprudence. Not yet reflected in the work of New Brandeis scholars is the internal economic critique of the Consumer Welfare Standard that caused most economists specializing in welfare economics to abandon it. The substance of this critique is that the Consumer Welfare Standard is biased and logically inconsistent. We maintain that the arguments of the New Brandeisian scholars would be strengthened by their recognition and incorporation of this critique by welfare economists. In addition, we raise questions about the New Brandeis scholars’ current replacement for the Consumer Welfare Standard, the “competitive process test.” What “competition” consists of is not obvious, and economic theory is not helpful in defining competition (except for “perfect competition,” which is irrelevant to antitrust). We suggest that the protection of competition standard as currently formulated continues to rely on the Consumer Welfare Standard. Finally, we contend that recent work in the social sciences and in welfare economics largely confirm the propriety of the goals on which the New Brandeis scholars’ approach is founded.