Use of Functional Neuroimaging in Forensic Contexts

Functional Neuroimaging in the Courtroom…So Far

• Establish competence to waive Miranda rights• Subjective experience of pain in tort cases• Custody determinations• Mens rea defenses for fraud, kidnapping,

burglary, and murder (even in sentencing phases of capital cases)

• Inferring past mental state• In juvenile cases

Brown & Murphy’s (2009-10) Opinions

1. Almost certainly more unfairly prejudicial than probative on balance

2. Favor Federal Rule of Evidence 403 to Daubert framework- 403: excluding relevant evidence for prejudice,

confusion, waste of time, or other reason- Daubert: admissibility of expert witness’ testimony- Allows for individualized assessment of claims- Room to allow the technology to improve and adapt

Functional Neuroimaging for Mens Rea Claims

• Mens rea – “guilty mind”– Mental state at the time of the crime

• Distinction between criminal mind v. criminal act

• Mens rea claims: defenses that attempt to make the prosecution’s case (for requisite mental state) more doubtful, and promote affirmative insanity

Functional Neuroimaging for Mens Rea Claims

• Steps for waging insanity defense (in most jurisdictions):– Defendant bears initial burden on raising the defense– Then, burden of persuasion shifts to the prosecution – Prosecution has to prove sanity beyond reasonable doubt

• Often hard for prosecution to do this– Criminal mind can’t be concretely measured– Intent is usually established by indirect measures (e.g.,

examining behavior surrounding the crime)

• Use of functional neuroimaging usually raised by defense– Physically difficult for the state to get a brain scan of an unwilling

person

Functional Neuroimaging for Mens Rea Claims

• Working assumptions that aren’t settled:– Brain state vs. mental state– Completeness of cognitive neuroscience

knowledge– Accuracy of self-reports/behavioral assessments – Accuracy of technology– Whether a behavioral task or a resting-state scan

explanatory enough to establish mens rea

The Science of Functional Neuroimaging

• Potential confounds can arise along the way in:– Poorly calibrated technology– Behavioral task

• “…limited…for determining mens rea so long as institutional review boards exist and research ethics are followed”

– Issues with data reconstruction– Preprocessing– Stats and thresholds– Semantics of data interpretation (e.g., “activation”, “functional

connectivity”)– Lack of reports for individual vs. group findings– Establishing a “baseline” and a “normal”

What would need to be done scientifically to make functional neuroimaging more

appropriate for a forensic setting (or will it likely never be)?

Admissibility

• To be admissible, brain images must be:– Relevant– Authenticated– More probative and prejudicial – Must satisfy tests for expert scientific testimony

• Not considered direct proof or evidence of mens rea, rather circumstantial demonstrative evidence

• Essentially never introduced without expert testimony

Relevance

• Materiality – fit between evidence and case– E.g., impulse control task would not be relevant in CA

because doesn’t recognize “irresistible impulse” as a claim for legal insanity

• Probative value – tendency of evidence to establish the proposition for which it is offered– Must have a reasonable explanation for using it– Must have a probabilistic connection between

evidence and proposition seeking to prove

Probative Value

• Varies

• For complex mental states and cognitive functions, almost no 1-to-1 mapping of brain region to function

• Neuroimaging knowledge comes from “forward inference” vs. direct manipulation of healthy brain tissue

• Most of the time, there could be another explanation for findings, meaning weak probative value

• Yet to be established for functional imaging are things like prior probabilities and base rates

Probative Value

• Might be more prejudice than probative because (i.e., why “jurors will likewise succumb to the seduction of fMRI”): – Jurors may view it as the ultimate truth due to its fanciness– Objectivity of brain images is overestimated– No procedure for standardization or replication– The use of colored blobs can make the image more salient and

reinforce the memory for it– Jurors might be led to think they are seeing the person’s brain,

when it’s actually a warped image– “neuro-essentialism” (brain is viewed as the essence of being

human)– CSI

Are there any cases now that functional neuroimaging would be more probative than

prejudicial?

Authentication• Demonstrative evidence can be admitted into the record if there is

sufficient proof that it is what the lawyer claims it to be (FRE 901a/104b)

• At present, no standard for authenticating functional brain images

• Issues for authentication:– Image must capture individual’s brain under the same conditions that existed

at the time of the crime– Procedure for creating the image must be described in detail– Underlying statistical computer programs must demonstrate reliance on

irrefutable scientific principles

• Basically, right now it’s just important that expert testifies that it only approximates mental state, is correlative in nature, and idiosyncratic decisions can alter what the data ultimately look like

Alternatives

• Look at the defendant’s behavior around the crime

• Use behavioral psychology

• Admit more images rather than fewer, so juror can determine the strength of the overall story

Competency (Ricker, 2012)

• Might be inappropriate also

• Mostly because we still don’t know how variables such as demographics can further influence functional neuroimaging

• Behavior is a stronger approximation

Deception Testing (Ricker, 2012)

• Two private companies in the US offer fMRI “lie detection” services

• Has been a shift in this field to do more individual-based analyses

• Accuracy of classification ~78% (Langleben et al., 2005)

Moral of the story, the authors of both articles think functional neuroimaging is not ready for

prime time yet.