What is the doctrine of consensus as applied by the European Court of Human Rights and how does it relate to the Court’s ‘living instrument doctrine’? This question is addressed in this chapter by paying attention to the definition, the function, the ascertainment and the outcome of the consensus doctrine. Among the many insights this chapter offers, two can be highlighted. First, the concept of opinio juris hominis is introduced in order to qualify a special kind of consensus that is directly related to human rights issues. This consensus carries more weight as it directly establishes a common understanding regarding a human rights issue. It is argued that the Court should continue to restrict the doctrine of consensus to questions of balancing and not to extend it to the interpretation of texts. The chapter demonstrates that Article 31, Section 3 of the Vienna Convention on the Law of Treaties offers all tools to deal with questions of interpretation. Other questions, such as whether differential treatment can be justified or whether a measure impacting upon human rights is necessary in a democratic society, can be dealt with by the consensus doctrine.