Neuroscience-based Mind-Reading in the Law (Part Two)

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An image from an fMRI-based mind-reading
experiment performed by Miyawaki et al in 2008

(Part One)

This is the second part in a short series on neuroscience-based mind-reading in the law. The series works off the article “What will be the limits of neuroscience-based mind-reading in the law?” by Murphy and Greely, which appears in The Oxford Handbook of Neuroethics.

In part one, we looked at some of the basic arguments in favour of using neuroscience-based mind-reading in the legal context, as well as the problems confronting such technologies. In this part, we will take it for granted that the technologies could deliver on their promises and consider whether they would actually have an important impact on the way in which the legal system works.

As Murphy and Greely note at the outset, the legal system seems, at first glance, like the ideal place for such technologies to be deployed. For starters, as pointed out in part one, the legal system is one place in which people might have an incentive to mislead us about the true state of their mind and, hence, it is one place in which traditional mind-reading techniques might be less reliable. Furthermore, in the legal system, the content and quality of a person’s thought is often of great importance.

Murphy and Greely give three examples of this. In the realm of personal injuries law, people can recover damages for experiencing “pain”. But pain is, of course, a mental state, one that those wishing to claim damages might be inclined to “fake”. So working out whether they really are in pain could be important. In the criminal law, a person’s guilt or innocence is often contingent upon their state of mind at a particular historical moment. So having some means for working out that state of mind could be beneficial. Finally, legal decision-making is best when it is free of bias, but bias is itself part of person’s mental framework. If we could use mind-reading to filter out biased jury members or biased judges, we could improve the quality of legal decision-making.

Despite the superficial appeal of these three examples, Murphy and Greely are keen to argue that the usefulness of mind-reading in the law is not as straightforward as it initially appears. Although mental states feature prominently in the law, the actual subjective state of mind of a individual litigant or defendant’s is not always that important. Sticking to their trinitarian ethos, Murphy and Greely offer three examples of this. I’ll discuss each in turn.


1. The Mental Aspect of Criminal Liability
There is a standard formula for criminal liability. Every offence is defined in such a way that it consists of a number of “elements”. These elements fall into two general categories: (i) external elements (actus reus elements) and (ii) fault elements (mens rea elements). In order to held criminally liable, the defendant in a criminal trial must satisfy both the external and fault elements of the offence. The fault elements are typically defined in terms of someone’s mental state, e.g. what did they intend or believe at the time of the offence.

The offence of murder provides an illustration of this. The external element of murder is defined (roughly) as “the death of one (or more) persons caused by the actions of another”, whereas the fault element is defined (roughly) as “the intent to kill or cause grievous bodily harm”.

At first glance, it might seem like mind-reading could play an important role in determining whether someone was criminally liable for murder. Although we noted in part one that there are problems associated with historical mind-reading, we are not going to be shackled by technological limitations here. Let’s speculate that, in the future, every human being is fitted, at birth, with a mind-reading device that records their brain states at every moment of their lives. This would effectively provide the brain equivalent of CCTV footage. If we had such a technology, and if we knew which mental states were correlated with which neural states, we could check to see whether, at the relevant time, the defendant actually intended to kill or cause grievous bodily harm. Hence, we could establish their liability for murder.

But this is not the end of it. Whilst knowing that someone intended to kill at a historical moment might be sufficient for a determination of criminal liability, it is not necessary for such a determination. One thing that has long been noted by criminal courts is that the subjective content of a person’s intentions might not be to kill, but nevertheless their subjectively intended action might have the obvious (or virtually certain) consequence of causing death. For instance, someone might plant a bomb on plane with the subjective intent of claiming an insurance payout, while lacking the intent to kill all the passengers. Still, the death of the passengers is a virtually certain consequence of their actions. Are we really going to say that such a person is not guilty of murder?

Most people think not. And criminal courts have developed doctrines of oblique (or indirect) intent to cover exactly these kinds of scenarios. As a result, people can be held liable for murder, despite not having the subjective intent to kill or cause GBH. What’s more, this is just the situation in relation to murder. In other cases, the mental element might be defined in terms of “recklessness”, and working out whether someone has been “reckless” typically involves considering the objective reasonableness of their state of mind, not just their actual state of mind. In still other cases — so-called strict liability cases — there is no fault element that needs to be proved.

While there are disputes about the moral propriety of how the criminal law determines liability, these examples illustrate how knowing what someone’s subjective state of mind was at a historical moment is not always that important in the criminal law. Oftentimes what we think an objectively reasonable state of mind would have been is what really matters.


2. Contract Law - Saying versus Thinking
This situation is replicated in other areas of law. Murphy and Greely next use the example of contract law. In order to create a legally enforceable contract, two or more parties must reach an agreement as to the terms and conditions upon which a good or service is to be bought and sold. To reach an agreement, there must be a “meeting of minds” between the two parties. That is to say, one party's mental picture or understanding of the agreement must match-up with the other's.

Again, given this description of the doctrine, one might think that mind-reading technologies could play an important role in determining whether or not a valid contract has been formed. But, once again, this is not quite true. The actual legal test for agreement depends, almost entirely, on objective factors. From what the parties said and did, does it seem like they reached an agreement? Would an objectively reasonable bystander think they had reached an agreement? And so on. The answer to these questions is not dependent on knowing the subjective states of mind of the parties. Thus, the potential for mind-reading technologies to help might be quite limited.

That said, Murphy and Greely are less dismissive of mind-reading in this context. As they point out, a reliable neuroscience-based mind-reading technology might still have an important role to play in contract law. For one thing, a reading of a person’s neural states at the moment when the alleged contract was formed might be a piece of evidence that goes towards determining whether the parties thought they had reached a deal. For another thing, it may be that the reliance on objective factors was just a way for the law to get around the practical difficulty of establishing what someone really thought. If mind-reading technologies remove this practical difficulty, then the law might revert to a largely subjective test of agreement. Finally, it may be that mind-reading could play an important role in contract negotiation, helping the parties to work out what one another really want and thus allowing them to craft an appropriate deal.


3. Tort Law - Where the mind may not matter at all
Tort law is complex. Basically, it provides a legal mechanism for a person (call them A) to claim damages from another person or persons (call them B), in the event that A is injured or harmed in some way. That’s the basic idea, but, as Murphy and Greely point out, there are different kinds of tort and each one has a different test for liability. Again, three examples are discussed.

First, there are such things as “intentional torts”, which require proof of intent to perform the tortious act on the part of B. The example the authors give is the tort of trespassing on another person’s property. In order to be liable for this, you must intend to be on another person’s property without their consent. A mind-reading device might have some utility here in proving whether or not you have the requisite intent.

Second, there are “negligent torts”. In these cases — which are the most common — B must owe A a duty of care, must have failed to live up to the standard of care owed to A, and A’s injury must have been reasonably foreseeable by B. In these cases, the state of mind of B counts for relatively little, objective factors count for far more.

Third, there are “strict liability torts”. In these cases, damages can be recovered from the mere fact that some injury or harm has been incurred, irrespective of B’s intent or state of mind with respect to that injury or harm. A classic example would be a product liability tort where a manufacturer can be held liable for injuries caused to a purchaser of their product even without proof of intent or, indeed, negligence.

One area in which mind-reading might become important in tort law is in determining the level of damages to be awarded. As noted at the start of this post, subjective states of mind, such as whether a person is experiencing pain or not, can be relevant here. Also, how much a defendant (like B) has to pay out in damages might depend on their state of mind. Punitive damages, which go beyond mere compensation for injury caused, are sometimes awarded if it can be proved that the defendant acted with “malice, oppression or fraud”.


4. Other potential legal implications of mind-reading
By peering beneath the surface of these three areas of law — crime, contract, and torts — we see how, despite initial appearances, neuroscience-based mind-reading might have relatively little to offer to the legal system. All three of these examples worked with the assumption that mind-reading might be used to assist legal decision-makers when making determinations of liability. In other words, they assumed that the legal system might like to support the use of mind-reading technologies. But of course the legal system may also wish to hinder or prevent the use mind-reading technologies, especially if these technologies impact upon the legal rights of participants in the legal system.

For example, a court might ban the use of neuroscience-based mind-reading evidence on the grounds that it would be unfairly prejudicial. The justification for this ban would be helped by the fact that some studies suggest that people are irrationally biased in favour of explanations that make use of neuroscience (Weisberg et al, 2008). Similarly, the results of a neuroscience-based mind-reading test might be banned on the grounds that they violated the privilege against self-incrimination. This would only apply if the test was not undertaken voluntarily and, to be honest, I reckon it’s pretty hard to administer an fMRI or EEG-based test to a non-compliant subject (definitely in the case of fMRI).

While I think these kinds of concerns have a legitimate basis -- and, indeed, might be used to support a more general right to cognitive liberty (or privacy) -- I sometimes worry about playing up these kinds of concerns. It seems to me that in worrying about these kinds of implications, far too much credibility is given to what is, at present, a nascent technology.

Anyway, I shall leave it there for now. I’ve skipped over one section of Murphy and Greely’s article which deals with standards of proof within the law. I hope to look at this in more detail at a later stage. Still, despite this omission, I hope I’ve given a reasonable overview and introduction to the topic.