What Empirical Work in Law Cannot Do

In one line

Data can show that a rule is not working and can never say what the rule ought to be, because no quantity of facts about the world entails a conclusion about what should be done.

In the wording a student can write in an exam: empirical research establishes what is the case, and it cannot by itself establish what ought to be the case, since a normative conclusion requires a value premise which no observation supplies; it also cannot establish causation from correlation alone, cannot generalise beyond its sample, cannot measure what it did not think to measure, and cannot settle the meaning of the concepts it uses.

Limit one: it cannot tell you what the law should be

The point in its plainest form. A survey may establish that most people do not know about free legal services. Nothing in that finding says whether the State ought to spend more on awareness, and nothing says it ought to spend it on this rather than on schools.

Why not. A conclusion about what ought to be done needs a premise about what matters, and observations are not premises of that kind. The move from what is to what ought to be requires a value, and the value comes from somewhere else: the Constitution, a statutory purpose, a moral argument or a political choice.

What follows for a dissertation. The recommendations chapter, chapter 1420, always rests on two things: a finding, and a standard. MU marks the suggestions, and a suggestion supported by a finding but no standard is a preference in the same way an unnamed criterion is, chapter 900.

And where a legal researcher's standard properly comes from. Article 39A; the four facets of access to justice in Anita Kushwaha, chapter 530; the declared purpose of the instrument itself, which is the strongest; or a stated moral or policy premise, openly stated as such.

Limit two: correlation is not causation

Two things varying together can arise three ways. One causes the other; the other causes the one; or a third thing causes both.

A legal example. Suppose districts with more legal services clinics show higher rates of legal aid applications. It may be that clinics produce applications; or that districts with more applications got more clinics; or that both follow from a more active District Judge.

What establishes causation. A design that rules the alternatives out: an experiment, which law rarely permits, chapter 1230; a comparison before and after a change; or a mechanism traced case by case, which is the case study's contribution, chapter 980.

And the discipline in writing. Use the words associated with, varied with or accompanied by, unless the design supports caused, and say what the design was.