This chapter explores how due diligence obligations operate in pratice and how their content is determined. The first part explores the factual conditions affecting the scope of a state’s duty to act with due diligence, which are identified in power over the source of risk and knowledge of the risk. The chapter critically discusses the concept of power of the source of risk linked to due diligence and explains the difference between this power and similar notions, like control, influence and jurisdiction. The chapter then argues that the other condition shaping the scope of a state’s duty to act with due diligence is knowledge of the risk and links this knowledge to the concept of state fault. The second part of the chapter discusses the legal and factual parameters affecting the content of due diligence obligations. After thoroughly appraising the concept of reasonableness, the set of variables influencing the degree of diligence expected of a state are identified in: the degree of risk linked to the primary rule; the nature and value of the legal interest protected by due diligence; the level of state capabilities; and the level of state control over the source of risk.