The Ethics of Testifying: Objectivity vs. Advocacy in Expert Work
By David Lombard, PhD, Licensed Psychologist, 30+ years in clinical and forensic practice
Forensic psychologists are bound by a clear ethical standard: findings should reflect the data, not the side that retained the evaluator. Most experts, myself included, believe they meet that standard. Research from the last two decades suggests the picture is more complicated, and I think attorneys deserve an honest look at what the science actually shows.
What "Adversarial Allegiance" Means
Adversarial allegiance is the tendency for an expert's conclusions to drift toward the position of whichever party retained them, even when the expert is using a standardized instrument and believes they're being fully objective. This research comes primarily from psychologists Daniel Murrie and Marcus Boccaccini, whose field studies and controlled experiments have documented the effect across a range of forensic contexts, including risk assessment and competency evaluation.
What the Research Actually Found
In one widely cited experiment, forensic evaluators reviewed identical case files, with the only variable being whether they believed they had been retained by the prosecution or the defense. Evaluators who believed they were working for the prosecution tended to assign higher risk scores to the same offender than evaluators who believed they were working for the defense, despite reviewing exactly the same information. Field studies of actual court proceedings have found a similar pattern: on structured risk assessment instruments like the Static-99R and the Psychopathy Checklist-Revised, prosecution-retained experts systematically score higher than defense-retained experts, even though the instruments are designed to produce consistent scores regardless of who's using them.
Why This Happens, According to Researchers
Researchers have proposed a few explanations, and they aren't mutually exclusive. Some researchers point to in-group allegiance, the same social psychological pull that makes people favor the side they're aligned with. Others point to confirmation bias: once an evaluator forms a working impression, they may unconsciously weigh ambiguous information in ways that support it. A third factor is self-selection: attorneys may be better at identifying and repeatedly retaining experts whose track record already tends to favor their side, independent of any bias occurring during a specific evaluation.
This Isn't About Dishonesty
It's worth being clear about what this research does and doesn't suggest. It isn't primarily a story about experts consciously slanting their findings for money, though that concern exists too. The more troubling finding is that allegiance effects show up even among experienced, well-intentioned evaluators who genuinely believe they're being objective. That's why the field has moved toward structural safeguards rather than relying on an individual evaluator's self-assessment of objectivity.
What Reduces the Risk
A few practices the field has increasingly adopted:
Documenting reasoning transparently, so a reviewer can trace exactly how the data led to the conclusion, rather than taking the bottom-line opinion on faith
Using structured, validated instruments rather than unaided clinical judgment, since structure at least creates a checkable record, even if it doesn't eliminate allegiance effects entirely
Joint or court-ordered referrals, where feasible, which reduce the pull toward a single retaining party by design
Awareness and training, since research suggests evaluators who are aware of allegiance effects and actively guard against them show less drift than those who assume the problem doesn't apply to them
What This Means for Attorneys
This research gives you a legitimate, well-documented basis for questioning any expert's findings, including your own side's. Reasonable questions include: Is the expert's reasoning fully documented and traceable to the data, or does the report lean heavily on a bottom-line opinion? Does the expert's track record, across many cases, show scores that vary appropriately with the facts, or does it always favor whichever side retained them? An expert who welcomes this kind of scrutiny, rather than treating it as an attack on their integrity, is generally more credible.
A Closing Thought
Knowing that objectivity is harder to achieve than it feels from the inside isn't a reason to be cynical about forensic work. It's a reason to build safeguards into the process rather than trusting good intentions alone, and it's part of why I try to make my own reasoning as visible and checkable as possible in every report I write.
If you'd like to talk through how these safeguards apply to a specific case, I'm glad to discuss it, alongside our Expert Consultation services more broadly. Contact me now.
Frequently Asked Questions
What is "adversarial allegiance" in forensic psychology? It's the documented tendency for a forensic expert's conclusions to drift toward the position of the party that retained them, even when using standardized instruments and believing they are being fully objective.
Does adversarial allegiance mean experts are lying? Not typically. Research suggests the effect occurs even among experienced, well-intentioned evaluators, likely through mechanisms like confirmation bias and in-group allegiance rather than conscious dishonesty.
What evidence supports adversarial allegiance as a real phenomenon? Controlled experiments and field studies, primarily by researchers Daniel Murrie and Marcus Boccaccini, have found that evaluators reviewing identical case information score risk assessment instruments differently depending on which side they believe retained them.
How can attorneys guard against allegiance effects in expert testimony? By asking whether an expert's reasoning is fully documented and traceable to the data, reviewing the expert's track record across multiple cases for consistency, and favoring experts who welcome scrutiny of their methodology.
Do structured assessment instruments eliminate allegiance bias? No, but they help. Structured instruments create a checkable record of how a score was reached, making bias easier to detect than with unaided clinical judgment alone.
References: