The Role of Brain Fingerprinting in Criminal Proceedings

The application of Brain Fingerprinting^® testing in a criminal case involves four phases: investigation, interview, scientific testing, and adjudication.  Of these four phases, only the third one is in the domain of science.  The first phase is undertaken by a skilled investigator, the second by an interviewer who may be an investigator or a scientist, the third by a scientist, and the fourth by a judge and jury.

This is similar to the forensic application of other sciences.   For example, if a person is found dead of unknown causes, first there is an investigation to determine if there may have been foul play.  If there is a suspect involved, the suspect is interviewed to determine what role, if any, he says he has had in the situation.  If the investigation determines that the victim may have been poisoned using ricin or cadmium, two rare and powerful poisons, then scientific tests can be conducted to detect these specific substances in the body.  Then the evidence accumulated through the test, the investigation, and the interview are presented to a judge and jury, who make the adjudication as to whether a particular suspect is guilty of a particular crime. 

In such a case, the science of forensic toxicology reveals only whether or not specific toxins are in the body.  It does not tell us when or where to look for toxins, or which toxins to look for.  We must rely on investigation to provide the necessary guidance on these issues.  The science of forensic toxicology also does not tell us whether a particular suspect is innocent or guilty of a crime.   The question of guilt or innocence is a legal one, not a scientific one, and the adjudication is made by a judge and jury, and not by a scientist or a computer.

Phase 1: Investigation

The first phase in applying Brain Fingerprinting testing in a criminal case is an investigation of the crime.  Before a Brain Fingerprinting test can be applied, an investigation must be undertaken to discover information that can be used in the test.  The science of Brain Fingerprinting accurately determines whether or not specific information is stored in a specific person’s brain.  It detects the presence or absence of specific information in the brain.  Before we can conduct this scientific test, we need to determine what information to test for.  This investigation precedes and informs the scientific phase which constitutes the Brain Fingerprinting test itself.

The role of investigation is to find specific information that will be useful in a Brain Fingerprinting test.  As with any scientific test, if the outcome of the Brain Fingerprinting test is to be useful evidence for a judge and jury to consider in reaching their verdict, then the information tested must have a bearing on the perpetration of the crime.  The job of the investigator is to find features relevant to the crime that have the following attributes.

1.      They are salient features that perpetrator almost certainly encountered in the course of committing the crime (e.g., the murder weapon or the escape route).

2.      The suspect has not been exposed to them in some other context, i.e., interrogation or court proceedings.

These features of the crime will be used in the Brain Fingerprinting test as probe stimuli.   If the suspect knows these specific features of the crime, and has had no access to this information other than through committing the crime, then this will provide evidence of his involvement in the crime.  If the suspect lacks this knowledge, this will provide evidence supporting his innocence.  Brain Fingerprinting tests for the presence or absence of this information stored in the suspect’s brain.

In some cases, the investigation will reveal no information about the crime that would be known only to the perpetrator and to investigators.  For example, in the case of a disappearance, investigators may not even know if a crime has been committed, and if so, what were the specific details of the crime.  In some sexual assault cases, there may be agreement between the alleged victim and the suspect as to all of the events that took place, but disagreement as to the intent of the parties.  Investigators may have made the mistake of revealing to the suspect all that they know about a case.  In such cases, no probe stimuli can be developed that will provide evidence relevant to the discrimination between a person who participated in the crime and one who did not, and no Brain Fingerprinting test will be conducted.

The investigator must use his skill and judgment in discovering and evaluating information to be used in the Brain Fingerprinting test, and any other evidence he uncovers.  There is always a degree of uncertainty in this process.  If the investigator finds a gun lying by the body of a person who apparently died of gunshot wounds, he may conclude that it is the murder weapon.  There is always a possibility, however, that it is not.  For example, perhaps the perpetrator shot the victim with one gun and planted another gun to frame someone else.   Ultimately, the evidence accumulated by the investigator will need to be weighed by the judge and jury for its bearing on the guilt or innocence of the suspect. 

Criminal investigation is not science.  Investigation does involve a high degree of skill and expertise.  The details uncovered by investigation are used as evidence in virtually every trial.  Expert testimony by investigators in criminal trials is very common.  When found to be relevant and based on reliable methodology, such evidence and testimony are universally accepted as a viable part of the proceedings in court.  This still does not mean, however, that investigation is science.  Unraveling the case and determining what is significant and relevant will always depend on the skill of the investigator.  Each case is different, and there is an infinite variety of information that may be available to be discovered.  There are no standardized algorithms or procedures that will solve every case.  There will never be a time when we can simply feed all of the facts about a case into a computer, and the computer will tell us what is significant or how the case is to be solved.  Although investigation is not science, investigation contributes substantially to legal proceedings, and the evidence and expert testimony provided by investigators will continue to be a valuable part of the process.

Some research scientists have expressed the view that if we just conduct enough research, and define and study a nearly infinite panoply of parameters, someday the process of investigation will become a scientific process that can be accomplished by applying a set algorithm which does not depend on the skill and judgment of the investigator.  There is no reason to believe – or to hope – that this will ever happen.  It is our view that science will not, and should not, take the place of skilled criminal investigation.   The infinite variety of factors in a crime, and the intimate involvement of human beings in every aspect of the crime, insure that the judgment and skill of the investigator will always be a necessary ingredient in criminal investigations.  Science will never make skilled investigators obsolete, and should not attempt to do so. 

The process of determining which items to use as probe stimuli will always depend on the skill and judgment of the investigator, and will never be accomplished just by applying some set scientific algorithm in the absence of human judgment.  Ultimately, the judge and jury will decide whether the evidence uncovered by the investigator and embodied in the probe stimuli is convincing regarding the guilt or innocence of the suspect.

Phase 2: Interview of Subject

Once evidence has been accumulated through investigation, and before the Brain Fingerprinting test is conducted to determine if the evidence can be linked to the suspect, it can in some cases be very valuable to obtain the suspect’s account of the situation.  For example, if an investigation shows that specific fingerprints are found at the scene of a murder, a suspect can be interviewed to determine if there may be some legitimate reason that his prints are there.  If the suspect’s story is that he was never at the scene of the crime, then a match between his fingerprints and the fingerprints at that scene would be highly incriminating.   If, on the other hand, the suspect’s story is that he was at the scene for some legitimate reason just before the crime, then fingerprints must be interpreted differently, particularly if there is corroborating evidence of the suspect’s presence at the scene before the crime.

The interview with the suspect may help to determine which scientific tests to conduct, or how to conduct the tests.  For example, a suspect may say that he entered and then left the room where a murder was committed a short time before the murder, and that he never saw or handled the murder weapon.  In this context, a finding that the suspect’s fingerprints matched the fingerprints on the doorknob would have little value, but a finding that his fingerprints matched those on the murder weapon would provide incriminating evidence.

Prior to a  Brain Fingerprinting test, an interview of the suspect is conducted.  The suspect is asked if he would have any legitimate reason for knowing any of the information that is contained in the potential probe stimuli.  This information is described without revealing which stimuli are probes and which are irrelevants.  For example, the suspect may be asked, “The newspaper reports, which you no doubt have read, say that the victim was struck with a blunt object.  Do you have any way of knowing whether that murder weapon was a baseball bat, a broom handle, or a blackjack?”  If the suspect answers “No,” then a test result indicating that his brain does indeed contain a record of which of these is the murder weapon can provide evidence relevant to the case. 

The suspect may have been exposed to information about the crime through an error on the part of interrogators in previous interrogations, through familiarity with the scene or the victim that has nothing to do with the crime, through hearsay from people directly or indirectly involved, or through any number of other channels.  It is vital that the suspect be given a chance before the Brain Fingerprinting test to disclose any familiarity he may have with the crime, so that any probes that he knows about for a legitimate reason can be eliminated from the test.  Recall that the probes contain crime-relevant information that the suspect has no way of knowing except through having been present at the crime.

The targets are also discussed in the interview.  Recall that the targets contain information about the crime that the suspect knows whether he committed the crime or not, and are used to establish a baseline brain response for information known to be significant to this subject in the context of the crime.  For example, if media reports known to the suspect have disclosed the location of a murder (e.g., “behind Newton Stadium”), then the location of the murder could be used as a target stimulus.  In the interview, the interviewer makes sure that the suspect does indeed know the information contained in the target stimuli.

In the interview, the suspect is also given a list of all of the stimuli to be presented in the test, without disclosing which stimuli are probes and which are irrelevants.  The suspect is asked to identify any stimuli that are significant to him for reasons that have nothing to do with the crime.  If any stimulus is significant to the suspect for reasons having nothing to do with the crime, then that stimulus is eliminated from the test.  For example, if the suspect claims to know nothing about who committed the crime and to be unfamiliar with any of the other people who are suspected of being involved, one of the probe stimuli may be the name of a known accomplice.  If that name also happens to be the name of the suspect’s brother-in-law, then the stimulus would be significant to the suspect for reasons unrelated to the crime, and this stimulus would be eliminated from the test.  In this way, the interview sets the stage for later interpretation of the test.  If the suspect has just told investigators that none of the stimuli are significant to him for any reason, and then the probe stimuli are revealed through Brain Fingerprinting to be significant to the suspect in the context of the crime, this scientific finding provides evidence relevant to the suspect’s involvement in the crime.

A frequently asked question is, “What if one of the probe stimuli is significant to the suspect for the wrong reason?”  The interview serves to eliminate this potential confound, as described above.

Things are significant to a person in context.  The context of the probe stimuli in relation to the crime is established in the interview, and prior to the Brain Fingerprinting test.  Immediately before each test, the context of the probe stimuli is established, and the probe stimuli are described without being specifically named.  For example, the subject is told, “In this test, you will see several items, one of which is the murder weapon.”  Then several different stimuli are presented, including the murder weapon (e.g., “baseball bat”) and several other options that would be equally plausible for an innocent person not familiar with the crime (e.g., “broom handle”).  We all have some familiarity with baseball bats and broom handles, but in the context of the murder in which the baseball bat was the murder weapon “baseball bat” will be significant for the perpetrator and not for an innocent suspect who does not know what the murder weapon was.

In some cases, the interview will reveal that the suspect is already familiar with all of the information that might be used to structure probe stimuli, for some reason unrelated to committing the crime.  For example, interrogators may have mistakenly revealed to the suspect all that they know about the crime.  In such a case, there is no remaining information to be used to structure probe stimuli, and a Brain Fingerprinting test is not conducted.  If a Brain Fingerprinting test were conducted to test whether or not a suspect knew details of a crime that had been told to him by investigators, the test would result in an “information present” result, which would be correct.  The probative value of such a result with respect to committing the crime, however, would be nil.  Such a test would only reveal, correctly, that the suspect knows the information.  Since the investigators already know for certain that the suspect knows the information – because they told it to him – this result would not provide any useful evidence with respect to solving the crime.  This is why a test is not conducted under such circumstances.  Note that this is a limitation only on when Brain Fingerprinting can be usefully applied, and not a limitation on the scientific accuracy or validity of the technique.  As with DNA, fingerprints, and every other science, there are situations where a correct Brain Fingerprinting result is simply not useful in solving a particular crime.

In short, Brain Fingerprinting determines scientifically and accurately what information is stored in a person’s brain.  It does not determine how that information got there.  In order for Brain Fingerprinting to be useful in identifying a perpetrator – that is, in order for a correct “information present” Brain Fingerprinting result to be useful evidence regarding a suspect’s participation in a crime – investigators must first discover information that would be known to a perpetrator but not to an innocent suspect, and ensure that the subject in question has not obtained that information through some means other than participation in the crime.  The interview contributes to this process.

Science is useful only when applied appropriately and intelligently.  If the aim is solving a crime or informing a judicial decision, then it is not useful to conduct scientific testing in a vacuum, absent any consideration of what the results will mean in the context of the crime.  A test must be structured that will provide relevant and useful results.  Also, once the results have been obtained, they are useful only if they are interpreted in the light of the other available evidence, as in the above example regarding fingerprints.  Brain Fingerprinting is like all other sciences in this regard. 

The interview serves to refine the selection of stimuli so that the test results will provide useful and relevant information, to establish the relevance of the stimuli, to eliminate potential confounds in the scientific test, and to provide a background for interpretation of the test results once they are obtained.

Phase 3: Scientific Testing with Brain Fingerprinting

            It is in the Brain Fingerprinting test where science contributes to the process.  Brain Fingerprinting determines scientifically whether or not specific information is stored in a specific person’s brain. 

Brain Fingerprinting is a standardized scientific procedure.  The input for this scientific procedure is the probe stimuli, which are formulated on the basis of  the investigation and the interview.  The output of this scientific procedure is a determination of “information present” or “information absent” for those specific probe stimuli, along with a statistical confidence for this determination.  This determination is made according to a specific, scientific algorithm, and does not depend on the subjective judgment of the scientist. 

Brain Fingerprinting tells us the following, no more and no less: “These specific details about this crime are (or are not) stored in this person’s brain.”  On the basis of this and all of the other available evidence, a judge and jury make a determination of guilty or innocent.

            It has been proven in the scientific arena, and also in court, that the science of Brain Fingerprinting has the following attributes:

1)      This science is testable and has been tested;

2)      This science has been peer reviewed and published;

3)      This science is accurate, has an error rate extremely close to zero, and has standard procedures for its application;

4)      This science is well accepted in the relevant scientific community.

These facts have been discussed extensively elsewhere, and will not be further elaborated here.  In legal proceedings, the science of Brain Fingerprinting may play a central role, but not an all-inclusive role.  The Brain Fingerprinting test is preceded by an investigation and followed by a legal determination, both of which fall outside the realm of science.

Brain Fingerprinting determines scientifically what information is stored in a person’s brain.  It does not determine how that information got there.  In order for a determination that certain information is (or is not) stored in a suspect’s brain to be useful to a judge and jury, the significance of this finding with regard to the crime must be established.  This is accomplished by the investigation and the interview, not by the Brain Fingerprinting test itself.  Brain Fingerprinting is similar to other sciences in this regard.   For example, as discussed above, a fingerprint test can determine that a suspect’s fingerprints match the fingerprints found at the scene of the crime, but the fingerprint test does not tell us whether that was because the suspect is guilty or because he was at the scene for a legitimate reason before the crime. 

Science can only provide scientific data – in the case of Brain Fingerprinting, a determination of “information present” or “information absent” regarding specific details of a crime in a specific brain.  Science, no matter how accurate and valid, is only useful in the context of an effective investigation.  For example, the investigator must determine whether or not there is some innocent, legitimate reason why a suspect’s fingerprints are at the scene of the crime in order for the scientific finding of a fingerprint match to have value in legal proceedings.  In the absence of adequate investigation, science – no matter how accurate and valid – may have little weight in the judicial process.   Brain Fingerprinting is no exception.   The investigation and interview that precede the scientific Brain Fingerprinting test are necessary to provide the information to test, and to provide a background as to the significance of the test vis-à-vis the crime once the scientific results are obtained.  The weight of the Brain Fingerprinting evidence, and its value to the judge and jury in making their determination, depend in part on the effectiveness and skillful execution of the investigation that precedes the scientific testing.

The science of Brain Fingerprinting does not tell us what information to test for.  This is determined according to the skill and judgment of the investigator – which is in the end evaluated by the judge and jury. 

Brain Fingerprinting does not test whether a person is guilty of a crime.  This is adjudicated by the judge and jury.  The question of guilt or innocence is a legal determination to be made by a judge and jury, not a scientific one to be made by a scientist or a computer.  What Brain Fingerprinting does is to provide evidence that can be weighed by the judge and jury in making their determination of guilt or innocence.

Phase 4: Adjudication of Guilt or Innocence

            The final step in the application of Brain Fingerprinting in legal proceedings is the adjudication of guilt or innocence.  This is entirely outside the realm of science.  The adjudication of guilt or innocence is the exclusive domain of the judge and jury.  It is not the domain of the investigator, or the scientist, or the computer.  It is fundamental to our legal system that decisions of guilt or innocence are made by human beings, juries of our peers, on the basis of their human judgment and common sense.  The question of guilt or innocence is and will always remain a legal one, and not a scientific one.  Science provides evidence, but a judge and jury must weigh the evidence and decide the verdict.           

The Role of Science in Legal Proceedings

In legal proceedings, the scope of the science of Brain Fingerprinting – and all other sciences – is limited.  The role of Brain Fingerprinting is to take the output of investigations and interviews regarding what information is relevant, to make a scientific determination regarding the presence or absence of that information in a specific brain, and thus to provide the judge and jury with evidence to aid in their determination of guilt or innocence of a suspect.

As with other forensic sciences, the science of Brain Fingerprinting does not tell us when to run a test, whom to test, or what to test for.  This is determined by the investigator according to his skill and judgment, and evaluated by the judge and jury. 

Recall the case of the possible murder by poisoning discussed above.  All the science of forensic toxicology tells us is that there is or is not ricin or cadmium in specific cadaver.  Science does not tell us to look for these specific poisons in this specific case.  This is determined by the investigator according to his skill and judgment. 

Similarly, the science of Brain Fingerprinting does not tell us what information to test for.  Again, this information is accumulated by the investigator according to his skill and judgment.  Brain Fingerprinting tells us scientifically whether or not this specific information is stored in a specific person’s brain. 

In the poisoning case mentioned above, science does not tell us whether a particular suspect is guilty.  This is determined by the judge and jury according to their human judgment and common sense.  The same is true of Brain Fingerprinting, and every other scientific procedure.

Again, the science of Brain Fingerprinting does not tell us if a particular suspect is guilty or not.  Only a judge and jury can make a determination of guilt or innocence, and they make this determination according to their human judgment, taking into account all of the scientific and other evidence.  It is our view that science, whether it be Brain Fingerprinting or any other science, does not and should not seek to infringe the realm of the judge and jury in making a determination of guilt or innocence. 

Nor is science a substitute for skillful and effective investigation.  Science depends on investigation, which is outside the realm of science, to determine when to test, whom to test, and what to test.  The evidence provided by science and by investigation ultimately must be weighed and evaluated by the human beings who are the judge and jury, on the basis of their human judgment and common sense, in reaching their verdict regarding the guilt or innocence of the accused.

It is fundamental to our legal system, and essential to the cause of justice, that the judge and jury must be supplied with all of the available evidence to aid them in reaching their verdict.  Brain Fingerprinting provides solid scientific evidence that must be weighed along with other available evidence by the judge and jury.   In our view, it would be a serious miscarriage of justice to deny a judge and jury the opportunity to hear and evaluate the evidence provided by the science of Brain Fingerprinting, when available, along with all of the other available evidence.  In the case of  a suspect presenting Brain Fingerprinting evidence supporting a claim of innocence, such a denial would also be an unconscionable human rights violation. 

Brain Fingerprinting is not a substitute for the careful deliberations of a judge and jury.  It can play a vital role in informing these deliberations, however, by providing accurate, scientific evidence relevant to the issues at hand.

Copyright © 2001-2002,  Lawrence A. Farwell PhD

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