For many years now, the legal academy has turned to economics for help in solving legal problems. Economics is obviously a powerful member of the social science family, and in today’s world it offers much guidance to policymakers who seek to understand core aspects of our national and global economies – which are increasingly based on a capitalist model. The field of economics, with its traditional core assumptions of rational actors and free markets, has provided a useful basis for analyzing many of the dynamics of these economic systems.

However, there are many other social science models available for understanding how law operates across multiple domains of life. Psychologists, for example, have employed a number of different models of how human beings operate – and not all of them begin by assuming rational action as the primary mode for human activity. Sociology, anthropology, political science, and some kinds of historical studies also have long traditions of empirical research on law that are not exclusively – or even largely – based in “rational actor” models.

Because New Legal Realism seeks to incorporate the wisdom of a truly interdisciplinary array of social sciences, it proceeds from a different foundation than the “rational actor” models of traditional economics. That is not to say that NLR approaches do not also include the study of rationality. A “rational” calculus about the best economic or strategic approach can be accurate in assessing how some people operate a lot of the time, or in assessing how many people operate when they are faced with choices within capitalist economic markets. However it is only one of many aspects of the way complicated people act, especially across many parts of their lives. They may, for example, make choices that are economically disadvantageous to themselves out of love, anger, social pressure, fear, emotional illness, and any number of other kinds of factors.

To understand the full picture of life in the real world for most people, it is important to develop a complicated model that takes account of rationality, emotion, culture, social structure, family influences, personal psychology, and other parts of their lives. These processes are not always governed by rationality. And, unlike “rational actors,” real people are sometimes at a disadvantage, unable to pursue what seems like a “rational” course of action because they are ill, elderly, poor, or otherwise vulnerable. Indeed, at times vulnerable people cannot take “action” – but they are still important “subjects” of the law. It is for this reason that the New Legal Realism advocates the expansion of core models for analyzing law beyond “rational actors” to “complex and vulnerable subjects.”

Complex subjects may calculate their most rational choices when deciding how to invest money (or they may not); and at the same time they may persistently behave in ways that undermine their own success when trying to parent their children after a divorce. The law has to contend with both of these kinds of situations, and many more; so sometimes the best information for legal reform in arenas like custody law comes from fields like psychology that specialize in understanding irrational as well as rational action. Or, in some cases, it may be that the legal system has to deal with people from quite different cultural traditions. In these cases, fields like anthropology, which specialize in cross-cultural translation, would be best suited to providing empirical information for legal professionals.

Vulnerable subjects cannot always exercise free choice because they are subject to constraints in the real world. They may be young, or sick, or elderly, or in some other way dependent on others for support. Focusing on vulnerability reveals a hidden distortion in the “rational actor” model; this focus helps us to see the way differing circumstances and power inequalities affect the people who are subjects of law.