2009 Defenders of the Innocent Event: Power of DNA

The Power of DNA

On May 18, Larry Marshall spoke at the Defenders of the Innocent Awards Reception on what DNA can achieve for the innocent.

The Power of DNA
by Larry Marshall
Defenders of the Innocent Awards Reception, May 18, 2009

Larry MarshallWe read about the DNA cases, and we say, “Oh boy, we’ve come so far, and we are succeeding so much in showing these people are innocent.”

But think about it for a moment. In a homicide case, there is only about a 20% chance that there will be biological evidence susceptible to forensic testing. If it’s a sex crime combined with a homicide, yes, there’s a higher chance.

But if, God forbid, someone walks through this door right now with a gun and then runs out after shooting, what are we going to have? Are we going to have that person’s DNA to test, to find out if we got it right or wrong?

No. We are not going to have DNA that will corroborate or confirm the accuracy of our identification.

What DNA Can Actually Do–Its Power

The power of DNA is that it helps expose to us that the answers we used to think were so reliable are after all not that reliable.

  • The eyewitnesses whom we used to think were the gold standard are prone to error, particularly when we are talking about cross-racial identification, particularly when we are not using state-of-the-art identification procedures that have been shown in the lab to minimize the risk of wrongful identification without minimizing hardly at all the accuracy of correct identification.
  • It is showing us that a system that relies on confessions alone, and particularly confessions that have not been videotaped, is not a system that deserves our trust.
  • It is showing us that jailhouse informants lie with great frequency—well, DUH. You are in prison. You have a belief—a right belief often—that if you say that someone confessed to you, you might get out of jail. How many of you can say that you would resist that temptation especially if you are told, “We know the SOB did it. We just need help putting him away.”
  • DNA has exposed other junk science—cases where people were on death row because some dentist came in and said, “Yes, I saw a bite mark on the victim and then I looked at the teeth of this suspect, and I can tell you to a medical certainty that this was the same person. These teeth made that bite mark.” With the benefit of DNA, the experts in the cases where it can be tested have seen that there is less than 50-50 accuracy on that. So it has been debunked.

And I could go on and on.