When Experts Go Rogue: Ethical Responses to Unethical Testimony in Forensic Psychology

As forensic psychologists, we operate in an adversarial legal system that demands not only intellectual rigor but also ethical clarity. Unfortunately, we occasionally find ourselves in the uncomfortable position of witnessing expert testimony that departs from professional standards, whether through overreach, bias, misuse of assessment tools, or outright conjecture disguised as clinical opinion.

How should we respond, especially when we are called to testify in the same matter? How do we uphold our own integrity while acknowledging, implicitly or explicitly, that another professional has strayed from best practices?

Let’s explore the ethical path forward.

1. Keep the High Ground: Lead with Data, Not Drama

The strongest rebuttal to questionable expert testimony is not a personal attack. It is better data.

Rather than commenting on an opposing expert’s motivations, background, or ethics, focus on:

• The standards of practice (such as the APA’s Specialty Guidelines for Forensic Psychology)

• Empirical evidence that supports or undermines a conclusion

• Methodological rigor or lack thereof

• What was or wasn’t done, not why it was or wasn’t done

For example, you might say:

“In forming my opinion, I conducted a clinical interview, reviewed collateral records, and administered standardized measures with documented forensic utility. My methodology followed national best standards as set forth by the APA’s Specialty Guidelines for Forensic Psychology and best practices identified in peer-reviewed literature. I did not see evidence that such tools or methods were utilized in the opposing expert’s report.”

That statement says everything it needs to without ever naming or shaming. It anchors your work in professionalism and science, while subtly highlighting the contrast.

2. Avoid Conjecture: Don’t Speculate, Don’t Diagnose from Afar

We’ve all witnessed experts crossing the line into speculation. A particularly infamous example occurred during the Johnny Depp defamation trial, when a psychiatrist testified about Depp’s cognitive functioning despite never having evaluated him. The psychiatrist made sweeping claims based on Depp’s behavior in films, opining on impulse control and cognitive decline as if cinematic performances were clinical samples.

This approach violates foundational ethical principles, including those of both psychology and psychiatry. Forensic mental health experts, regardless of discipline, are expected to ground their opinions in sufficient data and remain within the boundaries of their competence. In this case, the psychiatrist's testimony also arguably violated his own profession’s ethical standards, as outlined by the American Psychiatric Association’s Principles of Medical Ethics, particularly Section 7, which states:

“On occasion psychiatrists are asked for an opinion about an individual who is in the light of public attention or who has disclosed information about himself/herself through public media. In such circumstances, a psychiatrist may share with the public their expertise about psychiatric issues in general. However, it is unethical for a psychiatrist to offer a professional opinion unless he or she has conducted an examination and has been granted proper authorization for such a statement.”

This ethical breach was widely criticized during and after the trial. Estimating someone’s cognitive functioning based on movie performances and media appearances not only lacks scientific validity but also undermines the credibility of expert testimony in the public eye.

3. Frame Your Testimony Around Process, Not Personality

Rather than focusing on who did something wrong, focus on what was methodologically flawed. This protects you from sounding defensive or combative and keeps your testimony on ethical and intellectual ground.

You might explain:

• “Standard practice in forensic evaluations requires XYZ. That process was not followed here.”

• “The absence of structured data sources limits the reliability of the conclusion.”

• “This appears to be a clinical impression rather than a forensic opinion based on established criteria.”

Let the facts do the work.

4. When to Address It Directly (and When Not To)

There are times when direct critique is necessary, for example, if an expert has testified outside the scope of their license, misrepresented data, or engaged in a pattern of egregious conduct. But even then, it must be presented through a lens of professionalism, clarity, and objectivity.

In most cases, your job is not to police the other expert’s ethics. It is to present your own work with enough rigor and transparency that the contrast becomes self-evident.

5. Know Your Lane, Stay in It, and Know When to Speak

If an attorney asks you to comment on another expert’s opinion, you may be ethically permitted to do so, but only within limits. Focus on methodology and avoid motives. Stay grounded in your own evaluative framework and avoid being drawn into adversarial speculation.

A good rule of thumb: If you cannot support it with citations, records, or assessment data, do not say it.

Closing Thoughts: Elevating the Field by Example

Every forensic psychologist eventually encounters problematic expert work. The temptation to call it out harshly can be strong, especially when it compromises justice or makes a mockery of our science. But ethics, not emotion, must guide our response.

When you stay grounded in data, cite standards, and refuse to play dirty, you do more than protect your reputation. You protect the legitimacy of forensic psychology itself.