Rules of Origin (RoO) are among the most important instruments in the negotiation and functioning of Regional Trade Agreements (RTAs), designed to determine the eligibility of goods for preferential treatment among RTA members. Ostensibly meant to prevent the trans-shipment of imported products across RTA borders after only superficial assembly, they may act as complex and opaque trade barriers in practice. This book suggests that RoO do this with intent rather than accidentally. In other words, RoO are truly trade policy instruments. The book’s overall message for the policy community is that RoO are a potentially powerful and new barrier to trade. Their design should hold centre-stage in trade negotiations rather than being relegated to closed-door technical meetings.