Defending People

the tao of criminal-defense trial lawyering

Dealing With the State’s Expert: One Last Question

If you get a chance to talk to the State’s expert wit­ness before trial (if you’re allowed to, try; the best experts often see them­selves as neu­tral, and will explain their con­clu­sions to you), your last ques­tion should be: “What book should I read to learn about this topic myself.” Get the book; it’ll be a learned trea­tise that you can mine for cross-examination material.

In a Hous­ton mur­der trial once, for exam­ple, after the pros­e­cu­tor asked the med­ical exam­iner whether the knife wound could have been irreg­u­lar because my client twisted the knife, and the doc­tor assented to that propo­si­tion, I had him read this por­tion of DiMaio and DiMaio’s Foren­sic Pathol­ogy (if you try — or aspire to try — mur­der cases, you need a good library of foren­sic pathol­ogy texts) to the jury in its entirety:

The most com­mon rea­son for a large, irreg­u­lar knife wound is move­ment of the vic­tim as the weapon is with­drawn. Pros­e­cu­tors, how­ever, like to con­tend that this is due to the per­pe­tra­tor twist­ing the knife in the body after stab­bing the individual.

While we’re on the topic of expert witnesses …

The only way to cross-examine an expert wit­ness about his con­clu­sions is to know at least as much, if not more about the nar­row sub­ject of his tes­ti­mony that hurts you than he does. The trick is to define that sub­ject as nar­rowly as pos­si­ble. It’s not pos­si­ble for a lawyer to know as much about, say, pedi­atrics than a pedi­a­tri­cian, but it is pos­si­ble (maybe later I’ll talk about how) for a lawyer to know as much about the sig­nif­i­cance of hymenal notches as the same expert.

If you’re not fairly cer­tain that you know as much about your narrowly-defined sub­ject than the expert, then you’re ask­ing for trou­ble when you cross-examine him about his con­clu­sions. Also, if you are fairly cer­tain that you know as much about your narrowly-defined sub­ject than the expert, then you’re still ask­ing for trou­ble (because you might be wrong) but the trou­ble might turn out to be worthwhile.

There are lots of things an expert can be cross-examined on other than his con­clu­sions. For exam­ple, the government’s experts can be harsh crit­ics of the police inves­ti­ga­tion. If you can’t get up to speed on the sub­ject mat­ter, or if your own study con­vinces you that the expert reached inescapable con­clu­sions from the avail­able evi­dence, ques­tion him about the holes in the evi­dence made avail­able to him (try to tap into his frus­tra­tion at things not being done just right) or leave him alone.

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About The Author

Mark Bennett got his letter of marque from the Supreme Court of Texas in May 1995. He is famous for having no sense of humor when it comes to totalitarianism.

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2 Responses to “Dealing With the State’s Expert: One Last Question”

  1. Hunter says:

    Great points. Most of the experts I deal with are DWI tech­ni­cal super­vi­sors, acci­dent recon­struc­tion­ists and the occa­sional “drug recog­ni­tion experts.” I’ve never been both­ered much when they refuse to talk to me. Always makes great points on cross when you point out to the jury that this “neu­tral” expert refused to talk to me. Or that the state instructed them not to talk to me…

  2. Mark Bennett says:

    Hunter,

    True — often the best gift a wit­ness can give you is to refuse to talk to you. Always ask (unless eth­i­cal rules for­bid it).

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