Monday, May 19, 2008

Use adversarial system, redundancies to prevent wrongful convictions from faulty forensic science

The main solutions to faulty forensic science causing convictions of innocent people may lie, I've long believed, in using the adversarial system to create redundancies in forensic testing. It's needed because, for the most part, forensic science just isn't as accurate as most watchers of TV crime dramas may believe. A columnist at Forbes earlier this month ("What's wrong with CSI?,"May 2), Roger Koppl, wrote that:

to judge by the most comprehensive study on the reliability of forensic evidence to date, the error rate is more than 10% in five categories of analysis, including fiber, paint and body fluids. (Meaning: When the expert says specimen X matches source Y, there's a 10% probability he's wrong.) DNA and fingerprints are more reliable but still not foolproof. The 1995 study, in the Journal of Forensic Sciences, looked at proficiency tests labs take to see whether their work is sound.

More recent studies have also shown problems. Though a 2005 study in the Journal of Criminal Law & Criminology suggests a fingerprint false-positive rate a bit below 1%, a widely read 2006 experiment shows an alarming 4% false-positive rate.

Yet the public sees errors as gross anomalies. Like the time the FBI wrongly linked an Oregon attorney named Brandon Mayfield to the 2004 Madrid commuter train bombing that killed 200 people. The FBI had claimed a 100% match between fingerprints found at the scene and Mayfield, who was held for two weeks in federal custody. When the Spanish National Police got the real perpetrator, an Algerian named Ouhnane Daoud, the FBI had to admit its mistake. Mayfield accepted a $2 million settlement from the government.

Another debacle, this time involving DNA testing: Josiah Sutton served four and a half years for rape after the Houston Crime Lab tied him to crime-scene DNA. The lab was later found to be rife with problems, including a leaky roof that let rainwater contaminate evidence. Sutton was proclaimed innocent in 2004 and awarded $118,000 in reparations the next year.

Forbes editor William Baldwin (no bleeding heart liberal), declared in response to these data that, "When it comes to science, judges are steeped in a long tradition of welcoming junk into the courtroom." It's a hard point to argue. When even fingerprint matches aren't 100% reliable, and some forensic techniques yield 10% error rates, that means quite a few innocent people may be accused by faulty forensics, allowing actual offenders to go free. Koppl's data about errors in the softer nether regions of forensic science reminded me of this recent assessment:
At the "Actual Innocence" conference in Plano last month [in April 2008], former executive director of the National Forensic Technology Science Center Bill Tilstone told the audience that most "pattern evidence" - handwriting analysis, shoe and tire print comparisons, etc., has no research-based foundation at all. Much of forensic science is "soft" science, he said, that at best has not or even cannot be comprehensively tested for accuracy.
Given the subjectivity of much forensic analysis, IMO the key to minimizing forensic errors lies in redundancy, an idea Mr. Koppl also embraced.

The core problem with the forensic system is monopoly. Once evidence goes to one lab, it is rarely examined by any other. That needs to change. Each jurisdiction should include several competing labs. Occasionally the same DNA evidence, for instance, could be sent to three different labs for analysis.

This procedure may seem like a waste. But such checks would save taxpayer money. Extra tests are inexpensive compared to the cost of error, including the cost of incarcerating the wrongfully convicted.

He's on the right track, but I think Mr. Koppl hasn't quite yet found the best solution. The most efficient way to create redundancy in forensic science is to use the adversarial system. Instead of police sending evidence to three different labs, two is plenty if we simply provide funds for defense experts whenever government crime labs analyze evidence.

As Koppl notes, such redundant checks promote accuracy, justice and save taxpayer money in the long run by reducing overall error. How much would error be reduced? Here's how the math works:

Say a method of forensic analysis yields a 10% error rate, to use an example from the high end. If a second analyst examines the evidence, the redundancy diminishes the probability of error from 1 in 10 to 1 in 100 (.1 x .1 = .01). In the case of fingerprints, if the error rate currently is 1%, allowing redundant defense analysis would reduce the possibility of error to just one-one hundredth of 1% (.01 x .01 = .0001).

What's more, if the defense hires the second expert, it avoids questions of vendors coming up with similar results to cater to the same customer's agenda, making it more likely evidence will be thoroughly vetted and more accurate results discovered.

Recently Sen. John Whitmire identified one of the problems confronting the much-maligned Houston PD crime lab as its lack of neutrality, opining that the forensic lab should be controlled by a "neutral" entity. But forensic science isn't neutral, no matter who performs it. Rather than attempting to create a single neutral entity, IMO it makes a lot more sense to use the existing structure within the adversarial system to mandate redundancies and improve accuracy.

UPDATE: The author of the Forbes article, Roger Koppl, reacts.

See related recent Grits posts:


Anonymous said...

Peer review is often helps bring serious problems to the attention of top administration and the legislature.
The legislature could require periodic peer review of crime labs and they could also require random selection of cases for external review to keep the lab on-it's-toes.

W W Woodward said...


It sounds a little like you may be jumping the fence on this forensics business. In your May 17, 08 post “Valor Redefined” you seem to heartily approve the use of forensic methods when used by the defense “…the officer told a story that forensics disproved,..” “Blame the forensic analysts hired by the defense and the DA, not me, if you don't like the facts they've presented.” ”He said one thing, science proved another. The facts speak for themselves.”

I’ve been telling my law enforcement/jailor students for some time that all the TV shows dealing with forensics are not on primetime to educate the public, they’re there to sell beer. Forensics are a tool, used by both the prosecution as well as the defense to attempt to prove up a case or to create reasonable doubt respectively. It’ll all come down to which dog and pony show the judge or jury believes.

The adversarial system has been ?working? for sometime now. As to whether it is actually the best system, history may tell.

In my experience I’ve found that right and wrong quite often have nothing to do with the outcome of a trial. The outcome depends mostly upon which side brings the most and/or cutest monkeys to the circus. In my opinion, forensics is just another cute monkey.

Gritsforbreakfast said...

Not "jumping the fence," Woody. Read the rest of that post you're quoting from. What happened in that case? BOTH the defense and prosecution experts found the same thing - that the officer's story didn't hold up. Then read the part of this post again about the error rate diminishing when multiple analysts perform the same test.

I think forensic science is frequently valuable but also error-prone and agenda-driven. That's why you need both sides of the adversarial system to have access to their own experts, to doublecheck the other. (Koppl actually thinks they need to triple check.) Where's the contradiction?

Anonymous said...

The fact is that the sort of defense testing you advocate happens regularly. You will be hard-pressed to find a serious crime, in fact, in which appointed counsel for the defense have not been granted funds for forensic testing if they have requested it. I think you are right that that is a better method than duplicative testing in every case--after all, the defendant may know that the blood is his, or that the fingerprints are his, and won't request a retest in such a circumstance because it would only provide more evidence of guilt. But where the defendant may have reason to believe that the forensics are in doubt, it is quite common for the court to provide funds for him to have those forensics redone at a lab of his choosing.

Gritsforbreakfast said...

If the duplicative testing in is already done "regularly" and is "quite common," 4:19, bumping the frequency up to "always" won't be a big deal, then. Without duplicative testing in every case, of course, you get the high error rates which have produced so many erroneous convictions.

I think you misunderstood me when you wrote "you are right that that is a better method than duplicative testing in every case." I said and meant no such thing. In fact, perhaps the correct system is Koppl's "triplicate" suggestion, doing duplicative testing up front, once with police then again with a "neutral" lab, with defendants having a right to re-test if they disagree with the results.

With error rates between 1-10% for some forensic subspecialties, IMO it's irresponsible not to do duplicate testing at least on the less reliable ones up front.

W W Woodward said...

OK, Grits, point well taken.

I believe your statement, "I think forensic science is frequently valuable but also error-prone and agenda-driven." hits it pretty close.

Still a dog and pony show. "My expert is a better expert than yours."

Reasonable doubt!

Anonymous said...

Charles Kiker from Tulia here

Anonymous 4:19 said, "You will be hard pressed to find a serious crime . . . in which appointed counsel for defense have not been granted funds for forensic testing if they have requested it." I don't know how hard pressed one needs to be. But court appointed defense lawyers repeatedly requested extensive testing on the drug samples Tom Coleman submitted to APD for testing, and were repeatedly denied. Well, maybe those weren't serious crimes. But the jury sentences handed down would indicate they were.

Oh well, Tulia was an anomaly, an isolated case of criminal non-justice.