Book excerpt: How best to manage risk involving multi-valued human biological materials is the overarching theme of this book, which draws on the sourcing and supply of blood as a case study. Blood has ethical, social, scientific and commercial value. This multi-valuing process presents challenges in terms of managing risk, therefore making it ultimately a matter for political responsibility. This is highlighted through an examination of the circumstances that led to HIV blood contamination episodes in the US, England and France, as well as their consequences. The roles of scientific expertise and innovation in managing risks to the blood system are also analysed, as is the increased use of precautionary and legal strategies in the post-HIV blood contamination era. Finally, consideration is given to a range of policy and legal strategies that should underpin effective risk governance involving multi-valued human biological materials.