While scholars espousing ideological explanations have noted the correlation between the intellectual trends of the New Deal and International Shoe, they have not demonstrated the strength of this connection. Some merely assert that ideology caused International Shoe,12 while others point to only very general similarities between International Shoe and the ideology of the age.' 3 This Article attempts to strengthen the ideological explanation by examining closely the intellectual context of International Shoe. That examination reveals that the decision did not result simply from the expansion of interstate business or the inherent weakness of the Pennoyer system. Instead, International Shoe was caused primarily by the emergence of a new conception of the law and the role of the judge. It was only because judges saw the law through the lenses of sociological jurisprudence and legal realism that judges believed International Shoe was necessary to address interstate corporate activity.