In order to make sense of the field and to provide examples that might guide and inspire future research, it identifies and discusses five genres of scholarship.
1) Law as the dependent variable. This genre tries to explain why societies have the laws they do and why laws change over time. Early economic analysis tended to assume that law was efficient, while later scholars have usually adopted more realistic models of judicial and legislative behavior that take into account interest groups, institutions, and transactions costs.
2) Law as an independent variable. Studies of this kind look at the effect of law and legal change on human behavior. Examples include analyses of the Glorious Revolution, legal origin, and nineteenth-century women’s rights legislation.
3) Bidirectional histories. Studies in the first two genres analyze law as either cause or effect. In contrast, bidirectional histories view law and society as interacting in dynamic ways over time. Laws change society, but change in society in turn leads to pressure to change the law, which starts the cycle over again. So, for example, the medieval communal responsibility system fostered international trade by holding traders from the same city or region collectively responsible. Nevertheless, the increase in commerce fostered by the system undermined the effectiveness of collective responsibility and put pressure on cities and nations to develop alternative enforcement institutions.
4) Private ordering. A significant body of historical work investigates the ability of groups to develop norms and practices partly or wholly independently of the state. Such norms include rules relating whaling, the governance of pirate ships, and, more controversially, medieval commercial law (the “law merchant”).
5) Litigation and Contracts. Law and economics has developed an impressive body of theories relating to litigation and the structure of contracts. These theories often shed light on legal behavior in former times, including contracts between slave ship owners and captains, and the suit and settlement decisions of medieval private prosecutors.