DNA Expert Clarifies His Position

In a recent article in The Times (“O.C. DNA Testing Laboratory Is Nearing Test of Its Own in Court,” March 27), I was characterized as “a paid defense witness against the use of DNA evidence.” This characterization is snide and inaccurate. I am not against the use of DNA evidence. In my published writings on the subject, I have consistently said that DNA typing is promising and potentially very useful.

I believe, however, that DNA evidence should be used only after the laboratory’s procedures have been properly validated, only when the tests are performed in a manner consistent with acceptable scientific practice and only when the findings are presented to the jury in a responsible, accurate manner.

To the extent I have opposed the use of DNA evidence, it is because, in the rush to bring DNA evidence to court, these reasonable conditions on its use have frequently not been met.

Second, I am not currently a “defense witness.” I last testified about DNA testing two years ago. At that time I was paid at a rate identical to that of other expert witnesses who have testified on the issue, including those who have testified for the prosecution.

Apart from my academic writings, I am best known in this field not as a “defense witness” but as a defense lawyer. Last year I served as co-counsel for the defense in New Mexico vs. Anderson, a case that attracted international attention in the scientific community. For your information, my work on that case (nearly 500 hours) was performed without fee, as a public service.

WILLIAM C. THOMPSON, Associate professor, UC Irvine