New Zealand Law Society - Using brain fingerprinting in court

Using brain fingerprinting in court

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The technology that is going to shape our future is already here. Much like the introduction of DNA evidence, Forensic Brainwave Analysis (FBA) is a powerful tool which could change the way serious crime is investigated.

FBA is a neuroscientific technique where a brainwave known as the P300 wave and the following Memory and Encoding Related Multifaceted Electroencephalographic Response (MERMER) are measured to determine whether a person recognises information which has been provided to them. Many people believe this technique is similar to polygraphs (commonly known as lie detectors), however, polygraphs measure physical responses to stimuli and rely on inferences drawn from the reaction to these stimuli. In contrast, FBA measures subconscious brainwaves which signal recognition. This approach appears, at face value, to be an extremely reliable way of determining whether or not someone’s brain contains particular knowledge.

When you are shown stimuli you recognise, your brain emits what is known as a P300 wave and a following MERMER. This reaction can be applied to forensic investigation using three types of stimuli: known information, unknown information, and probe information.

The known information is supplied by the tester to the subject to get an accurate initial reading of that person’s particular P300 wave and MERMER. The unknown information is information the tester knows the subject does not know, often because the information is made up. This unknown information is used to determine the person’s non-recognition brainwaves. Finally, the subject is supplied with probe information which would only be recognised by a person who was at the scene or event being tested. This probe information is distinct. To use a murder scene as an example, probes could include: the murder weapon, number of stab wounds, the fact that the victim was found lying face down, the victim was wearing bright red shoes or had short brown hair or that there was a large full-length mirror at the back of the room the victim was found in.

By running through these three types of stimuli repeatedly and comparing the results of the different types of brainwaves, it can be determined whether or not the person had knowledge of the probe information. If the probe information pertains to a crime scene only, people who had been at the scene would recognise this information. This technology allows inferences to be made as to whether a person was at a scene or not.

Subconscious brainwaves

Many people believe they have control over the way they think, what they think, and what they recognise. This may be true for some people’s conscious thinking, but our brains emit subconscious brainwaves which we have no control over. They are the brain’s immediate reactions to assist us in processing data we receive. Because the P300 wave and MERMER are subconscious, it is likely impossible to manipulate it. The system has extremely high accuracy when used correctly. To date it has not produced a false positive or negative since the analysis of the MERMER following the P300 wave was introduced.

This technology is comparable with DNA evidence. This means it may be subject to some of the same issues. A key issue with DNA testing is the introduction of human error throughout the DNA analysis process. When used correctly, FBA and DNA analysis give very accurate readings. The danger of such a high level of accuracy is that inaccuracy can still be caused by human error. Any human error could have serious consequences for the involved parties due to the perception that the technology is perfectly accurate. Using a technology so powerful comes with responsibility to ensure it is being used in such a way that minimises human error.

Legal application

We must start thinking about the possible legal application of FBA and other upcoming technologies. FBA raises issues that go to the heart of law as brain fingerprinting could arguably be more powerful in court than a DNA match. People tend to trust DNA evidence because of its high level of reliability. Technology which provides objective, science-based evidence inevitably becomes trusted among people.

This kind of technology also raises issues about fairness to defendants. As our technology develops and new investigative techniques are developed, it will be important to bear in mind some of the fundamental concepts about fairness which are entrenched in our legal system to prevent them from eroding defendants’ rights. For example, with technology such as FBA it will be important to consider whether defendants can be compelled to undergo FBA. Is it right to allow these types of tests to be conducted against a defendant’s will? These are the types of questions which must be at the forefront of our minds as we push into newer and more powerful investigative techniques.

We are at a crossroads. As a society, we should be asking if this type of technology is something we want in our legal system. We need to accept that new technology is not only coming, but is already here. Let’s start having the necessary conversations about what we do and do not want. We need to openly discuss the future of our legal system.

For more information please refer to Palmer, R. (2018) “Time to Take Brain-Fingerprinting Seriously?” Te Wharenga-New Zealand Criminal Law Review, 330-356.

Emma Pairman is a Crown Prosecutor at BVA The Practice in Palmerston North. Emma was part of the forensic brainwave analysis research team at Canterbury University in 2017.

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