Hume criticized the idea that all legitimate government rests on consent of any sort, tacit or express. He did not deny that some governments originated that way, or that it was an admirable way. But he thought it absurd to claim that legitimate government authority is contingent upon each subject’s consent. To say that it is so is contrary to common opinion and, moreover, simply shifts the question to that of the bindingness of promises. That bindingness must rest on the idea of necessity, and so it is needlessly indirect to appeal to promises when government can be justified directly by its necessity to prosperous and secure society. Hume, however, also made a positive contribution to the social contract tradition. He described how a convention, or common practice, can coordinate expectations and behavior without the need for any express agreement or contract. Later theorists make use of Humean convention in order to connect the idea of hypothetical consent to the actual circumstances of life. In short, government is legitimate where there is a convention of conformance to a social contract that would, hypothetically, be approved by clear-minded individuals.

This chapter explores how international law and its legitimacy could be improved and made more aligned with the demands of justice. It focuses on two types of requirements. First, there are the principles and accompanying procedures on the basis of which actors ask their agency (and their rights) to be recognized by international law and its culture of legitimacy. These principles are consent, justification, accountability, consistency, representation and participation, and non-abuse of power. Second, there are the topics around which this quest for the recognition of agency (and rights) takes place. They are better universality of international law, human rights as a benchmark of the legitimacy of sovereignty, compliance/enforcement/accountability, and human rights supported by public goods. These two kinds of requirements have been at the center of the efforts to make international law more inclusive as well as more legitimate, and they need to be taken more seriously in the future.

Political legitimacy entails a process of evaluation and eventually of judgment concerning whether or not, and to what extent, the exercise of political power (institutions, leadership, policies, and results) meets the conditions required by legitimacy. Despite the importance of the contribution of law to legitimacy, legitimacy cannot be purely and simply identified with and reduced to law. This is, in part, the case because law functions as an expression and vector of two other components of political legitimacy: values and consent. As such, this chapter is organized into three parts. First, I examine the meaning of values and consent and of their relationship in general. Second, I refer to the challenges that can be associated with values and consent. Third, I show how values and consent, provided that they are not the captives of these challenges, can operate as sources and criteria of evaluation and judgment of political legitimacy.

Recent empirical work demonstrates that some instances of material deception are perceived by ordinary people as consent-defeating, whereas other instances are not. One hypothesized account of these divergent lay intuitions draws on the notion of “essence”: Roughly speaking, lies that pertain to the “core” or “nature” of a consented-to act are perceived as precluding consent, whereas lies that pertain to features that are “nonessential” or “collateral” to the act are perceived as compatible with consent. To assess this hypothesized account, an independent measure of “essence” – one that does not rely with problematic circularity on notions of consent – is needed. This chapter draws on an emerging cognitive science literature that deploys linguistic probes to investigate how people intuitively represent human action. Here, we will consider two such probes, the “by” test and the “basically doing” test, and observe that whereas the former predicts judgments of consent, the latter does not.

What makes a constitution legitimate? Models grounded in consent, right procedure, or necessary and sufficient justice conditions capture powerful intuitions, but face equally powerful problems: These models generate paradoxes and infinite regress, and their static character ignores legitimacy’s dynamism. Moreover, debates around constitutional interpretation – originalism, living tree, or common good oriented - demonstrate the permanent space between a (constitutional) rule and its application. These debates leave mysterious how legitimacy, once in a constitution, ever gets out. But these issues resolve if we understand legitimacy as something functional, not substantive. Like a currency, I suggest, it can be drawn from diverse (normative and symbolic) sources, banked (in constitutions), and later withdrawn and spent (on political endeavours). This model honours normative intuitions, while escaping puzzles and paradoxes. Moreover, since a constitution’s legitimacy ‘holdings’ can fluctuate with political skill and circumstance, this model capture’s legitimacy’s dynamism. Such a functional model bridges the empirical and normative study of legitimacy, and it may deepen empirical understanding of normativity’s role in regime stability and constitutional change.

Modern law allows some adults to agree among themselves on allocating parenthood through adoption, preconception agreements, surrogacy, and voluntary acknowledgments. These doctrines cannot be justified by the adults’ intentions, promises, contracts, or similar social conventions. Those powers rest on agents’ authority over their own lives; no one can have a personal right to decide who will control a child’s life. However, liberal justice requires such legal authority. Many reasonable citizens value childrearing irrespective of biological ties and should have a derived liberty to pursue families. Excluding citizens from parenthood denies them fair equality of opportunity. Modern parentage agreements empower nonbiological parents to build families in ways that respect themselves, the child, and other parents. Adoption empowers an adult to create parenthood through an express commitment, subject to state oversight to protect the child and existing parents. Second-parent adoption and acknowledgments of parentage enable a single parent and their partner to agree to share parenthood prospectively, which prevents subordination in familial projects, protects the child’s relationships, and facilitates equality for lesbian and gay adults. Preconception agreements do likewise for a gestational parent and their partners. Well-designed regulations may render gestational surrogacy consistent with equal respect for the surrogate and women generally.

In the late Roman empire, the papacy’s endorsement of marriage as a divine institution was already explicita. From the mid-fifth century, fundamental importance was attached to the signification by marriage of Christ’s union of the Church, a value shaping the social practice of marriage, underpinning the creation in Roman Catholicism of a marriage system unique in the history of literate societies, one which banned both polygamy and divorce. More flexible laws limited marriage within the “forbidden degrees” of relationship. The aim was to foster social cohesion. These rules could be changed, or dispensed with, in individual cases. Marriage was made by consent, and only from the Council of Trent was the presence of a priest required. Christianity in general and papal law in particular slowly transformed the relationship between slavery and marriage.

This chapter explains the law surrounding consent for the medical treatment of children, when children can give consent themselves, who can give consent of their behalf and when a refusal of consent should be respected. It also considers guidelines relevant for the practice of restraint in paediatric anaesthesia. Finally, it discusses the unique features of the ethics of research involving children, including the levels of risk that are deemed acceptable.