Truth-Market Failure

by Roger Koppl



A friend of mine is a public defender in the Midwest.  These days she is working on a murder case.  The county medical examiner (ME) testified for the prosecution in the case.  The defense called in an ME from a neighboring county to testify for the defense.  The two MEs have opposite opinions in the trial.   To an academic, it’s normal for two experts to disagree.  But to a prosecutor it can seem outrageous that someone on “his team” would testify for the defense, even if in a different jurisiction. 



The district attorney (DA) in the county where the defense ME works fired off an email protesting “the testimony of you or a member of your office as a defense expert in a prosecution being conducted by one of my colleagues.”  Notice that this objection is not coming from the prosecutor in the case.  It comes from the prosecutor in the county where the defense ME works.  One of his MEs has the gall to go and testify for the defense in a nearby jurisdiction.  Unthinkable!


The email says, “I do not find this acceptable” and “I view this practice as a conflict of interest and inappropriate.” I think the DA sincerely believes that his ME acted wrongly.   “I would never accept a request to review the matter in the first place. Nor do you have to accept these requests. If you continue to do so, I am giving you the courtesy of letting you know that neither the Sheriff or I will be in a position to continue to support your appointment as the [local] County Coroner.”  That’s quite a threat: If you persist in testifying for the defense in other counties you’ll lose your job as ME in this county.



From the legal point of view it seems sort of obvious this was improper behavior, although I’m not jurist.  Medical examiners and other forensic experts are supposed to be neutral and speak only the truth.  How to you square that supposed neutrality with the view that it is somehow wrong to give evidence favorable to the defense?  But let’s look at it from the economic point of view.  From that angle, it looks rather like an attempt to establish and maintain a monopoly on truth.  There are only so many forensic pathologists out there.  If medical examiners cannot testify for the defense in other jurisdictions, then the supply of expert defense witnesses shrinks correspondingly, thus increasing the monopoly power of prosecution witnesses.  We oppose monopolies in the production of commodities, and we should oppose monopolies in the production of truth, too. 



We can start to see how to improve the system, I think, when we view the criminal justice system is a truth market.  And it seems to me that we need of improved market design in this area.  What changes would help?


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