Causation in Law and Medicine

Danuta Mendelson, Ian Freckelton, Ian Freckelton

• Publisher: Routledge
• Year: 2017
• ISBN:
  9781351953023
• Edition: 1
• Topic: Law
• Subtopic: Medical Law
• Index: Law

Causation is an issue that is fundamental in both law and medicine, as well as the interface between the two disciplines. It is vital for the resolution of a great many disputes in court concerning personal injuries, medical negligence, criminal law and coronial issues, as well as in the provision of both diagnoses and treatment in medicine. This book offers a vital analysis of issues such as causation in law and medicine, issues of causal responsibility, agency and harm in criminal law, causation in forensic medicine, scientific and statistical approaches to causation, proof of cause, influence and effect, and causal responsibility in tort law. Including contributions from a number of distinguished doctors, lawyers and scientists, it will be of great interest and value to academics and practitioners alike.

Part A:
The Concept of Causation in Law, Medicine and Science

1 Principles and Values Underlying the Concept of Causation in Law

ANTONY HONORÉ*

Introduction

What principles and values underlie the concept of causation in law? This brief discussion of a far-ranging question will concentrate on values. Of special interest to the consideration of causation in law and medicine is whether different values underlie the concept of causation in the two disciplines. I argue that the values underlying the concept are the same in both, but that the values underlying law and medicine differ. A consequence of this is that law and medicine are concerned with different types of cause and use the concept for different purposes.

Some values hold good outside law and medicine. They are important in everyday life even in areas which are no concern of either. Others are values of the legal system, in particular of adjudication. An example is procedural fairness. Without procedural fairness adjudication is unjust. And healing and the relief of suffering is a value specific to medicine. In my view, however, no value underlies the concept of causation in law or causation in medicine as such. The notion of cause is the same in law, medicine, science and everyday life. This point is one that common law judges have often stressed, when they say that causation in law is a matter of common sense. Whether one thing has caused another is to be judged by criteria that prevail outside the law.

Three topics will be dealt with in the light of this distinction between values that mark everyday life and those specific to law or medicine. These topics are causation, responsibility and legal liability. The concept of cause dominates our inquiries into the processes by which things happen, or have happened. Responsibility for good or bad outcomes of human conduct forms the link between causation and legal liability. It is central to the assessment of people's lives and doings, their successes and failures. But both causation and responsibility, though important in law, are concepts drawn from everyday life. The third topic is specific to law. It concerns the conditions that, in the interests of fairness, limit the extent to which people can be made liable for causing harm.

It may help to list at the outset the values that will be mentioned. In my view those that underlie causation concern the external world, which is, within limits, conceived as objective, regular and knowable. The knowledge that we acquire with its help enables us to survive in an uncertain world. That we should be responsible for our conduct and its outcome serves a different set of values. It encourages people to act in a way that will lead to good outcomes and it promotes a sense of personal identity. The restrictions on legal liability for harm caused to others rest on various aspects of fair adjudication, especially fair procedure. Fair adjudication is obviously not a medical value. Though the concept of cause is also not specially medical, its role in providing explanations of disease and recipes for cure is crucial to medical science and practice.

Values Underpinning the Concept of Cause

To take Kant as a starting point, causation can be thought of as a category, like space and time, built into our make-up. We cannot help conceiving the external world in terms of it. If Kant is right, it follows that it is an across-the-board notion, applied not only in law but in science, medicine, history, ethics, politics and, if it comes to that, cricket. The concept of cause is the same in every sphere of life. That the moon's shadow caused the eclipse of the sun; that the defendant's speeding caused the plaintiff's trauma; that the Plasmodium parasite caused the patient's malaria; and that Steve Waugh's leadership was the cause of Australia's victory in the World Cup – all apply the same notion. Causation is an all-purpose tool for inquiring into the relation between one event and another.

Some philosophers and lawyers conceive the cause of an event as a necessary condition (sine qua non) of the outcome, others as a condition that, along with others, is sufficient for the outcome. Whichever view is preferred,¹ a cause is something like an ingredient in a recipe: an element in a combination that, if repeated, will yield a similar outcome. Both views presuppose that we can generalise about the way things happen. We can say that when conditions A, B and C are present together this will lead in stages to D but that if A is absent and only B and C are present D will not follow, at any rate not by the same stages. Observation and experiment pick out the conditions that in combination consistently give rise to processes that yield a given outcome. The recipe idea has been refined to such an extent that with its help a rocket can be dispatched to Jupiter in the reasonable expectation that it will get there at a given moment. At a more mundane level the recipe idea applies to medical therapy. Given the patient's condition (A and B) doctors try to find a treatment (C) that will result in a cure. And if causation can be used in a forward-looking way to provide recipes it can also be used in retrospect to explain events, for example to diagnose illness.

To say that one thing caused or will cause another is therefore to refer indirectly to what happens in general. But in practice the sort of A,B,C formula just set out is not easy to discover or to apply to a given sequence of events, partly because the relation of particular to general varies with the type of process analysed. In the world of physics we can specify rather precisely what conditions will lead to what outcomes. Otherwise we could not send a rocket to Jupiter. Organic matter is less easy to analyse in terms of causal sequences because living creatures are complex. Members of a species do not react in a uniform way. The confidence that can be placed in judgements of cause in medicine differs from that in physics even though the concept of cause remains the same. A doctor may believe that, given complete knowledge of the relevant conditions, he could predict exactly the outcome of treating a patient with a certain drug, yet in practice seldom be able to do so. Patients do not react in the uniform, way in which rockets do. Medical science of course assumes that the condition from which a patient is suffering has a determinate cause and that the therapy will have a determinate effect. But often this does not make it possible either to diagnose or to treat the condition with confidence. Doctors have to go by probabilities, based for example on the frequency with which a certain drug is followed by a cure, even when the details of the process are unknown. It was reasonable to assume that penicillin attacked streptococcal infection and that most of the patients suffering from this infection to whom penicillin was given recovered because of it, long before anyone could show how this happened. Lawyers need, I think, to bear this in mind when weighing medical evidence that is couched, as it often has to be, in causal terms. The causes of most diseases lie in a complex of factors any one of which can be said only to contribute to the pathology.

If the concept of cause is hard to apply in the organic world of living matter it is not clear that it applies at all to the way in which human beings decide what to do. When people decide what to do they have reasons for deciding. But we need not and often do not think that these reasons would persuade everyone in a similar situation or that they would persuade the same person on another occasion. It is not clear that, if we knew all there was to know about the person who has to decide what to do, we could predict their decision with certainty. The decision need not be seen as an instance of a general law about the way in which human beings in general, or that particular person, react. For this reason the law, which is deeply concerned with human decision and action, often employs concepts that are only loosely analogous to causal connection in the world of inorganic or organic matter. The difference between human decision-making and the material world is marked by speaking of reasons for deciding and acting rather than causes. Advising someone to invest in a certain stock, even if they take the advice, is not the same as causing them to invest in it. But there is an analogy between deciding to act for a certain reason and being subject, as we all are, to the principles of physics and biology. To be satisfied that a person acted for a given reason, say that they invested on the advice of their stockbroker, we must believe that in the mind of the person to whom the stockbroker's advice was given it was sufficient to induce them to make the investment.²

What values, then, does the concept of causation serve? It presupposes three features of the external world that help us to survive. It assumes that the world we live in is within limits objective, regular and knowable. To the extent that this is true we can understand what happens around us and achieve at least some of our aims. The external world is conceived as objective in that it exists independently of us. But it does not follow that the way in which we conceive it is independent of our make-up and situation. For example, according to the theory of relativity certain data are relative to the position and motion in space and time of the subject observing them. Though there is an external world independent of us, it is plausible to think with Kant that the way we are made, and with Darwin that our need to survive, structure the way in which we see it.

A second value presupposed by the concept of cause is regularity. We are aware not merely of an objective world but of one in which patterns repeat themselves so that when similar conditions are present in different times and places similar outcomes follow. The universe treats like cases alike. But, as noted, our access to reliable generalisations is greater in the world of physics than in the world of living matter. This is not because causal regularities are not present in the organic world, if we can get at them, but because it is more difficult to get at them. It is less clear that causal regularities govern human decision-making and action. We do not and perhaps cannot know if determinism is true. So, even if causation is a category from which we cannot escape when we analyse the external world, it does not follow that we have to analyse ever...