The Cartagena Protocol on Biosafety (BP) is the first protocol to be negotiated under the Convention on Biodiversity (CBD). The BP promotes shared responsibility for conservation objectives in situations where they may be negatively influenced by international trade in genetically engineered organisms (called living modified organisms, or LMOs, in the BP). The “advance informed agreement” (AIA) procedure is its central mechanism. This chapter first examines the emergence of the AIA as an international norm in the trade and environment context, starting with its origins in “informed consent” around the mid-20th century. Second, the chapter examines the conceptual components of AIA/informed consent as they have been applied in biomedicine and other international treaties, highlighting the interpretive and practical challenges, and consequent strengths and weaknesses, of their application in the biodiversity context.