This thesis originates in a 'family anomaly' in European private international law. Conflict experts have observed a methodological shift towards regulatory and policy considerations in transnational economic relations. Fears of the dangers of an unregulated market have generated policy-oriented rules and overriding mandatory provisions. Experts are generally supportive of this paradigm shift. They reject the view that conflict of laws consists of a set of ‘neutral’ techniques designed to protect decisional harmony and parties’ expectations, the classical objectives of private international law. Some regard this as evidence of a long-awaited 'European Conflicts Revolution'. A paradigm shift is also occurring in the law governing cross-border family relations. Here, however, changes take the opposite direction as party autonomy and the method of recognition are being progressively constitutionalised. In contrast with cross-border economic matters, policy-oriented rules and mandatory norms evoke the 'ancien régime' and the exceptional characterisation of family relations that became dominant in the 19th century. Autonomy and recognition are popular because they come across as technical devices that liberate individuals from conservative social forces. For some, the contemporary turn indicates an evolutionary movement from government control to self-determination, ‘from status to contract’. Rather than portraying the family anomaly as part of a methodological revolution or as an evolutionary progress, this study advances a transformative thesis. Contrary to what is assumed, this study shows that private international law does not consist of technical rules and methods that develop in isolation from cultural and political processes. Tracing a genealogy of the law governing cross-border relations from the medieval to the contemporary age indicates that private international law constitutes an 'instrumentum regni' which is transformed by dominant ‘modes of thought’. Ideas and assumptions which prevail in legal consciousness have shaped the boundaries and functions of conflict of laws. In turn, the law governing cross-border relations has played a crucial role in articulating and consolidating sovereign power. In this light, the thesis shows that the family anomaly reflects the renaissance of ideas dating back to the age of classical legal thought, and most notably the contraposition between the family and the market, and their adaptation to a new cultural and institutional environment. It suggests the rise of a post-national institutional model which is illustrated by the profound redefinition of the way in which individuals form and dissolve civil and political bonds through conflict rules.