Junk Science in Court: Bite Me

If you were charged with a crime in the U.S. and put on trial, would you assume that the forensic evidence introduced in court against you would at least be based on some kind of sound, factual, scientific research? Think again.

Frontline recently ran a documentary on the “science” of fingerprinting, bite mark analysis, and other forensic “sciences” and demonstrated rather convincingly that many courts will allow testimony by self-styled experts that has no basis in any substantive research whatsoever.

The most dramatic examples were related to two men who had been in prison for ten years or more for assaulting and murdering three-year-old girls. In both cases, the men were the former boyfriends of the girls’ mother. In both cases, an orthodontist who claimed to be versed in the science of bite mark analysis testified that scratches on the little girls’ bodies were actually bite marks that could only have come from the suspects, to the exclusion of everyone else. In each case, this testimony was the bulwark of the prosecution’s argument. In each case, the judge allowed the testimony. In each case, the man was convicted. In each case, DNA analysis– which is founded in real science– eventually exonerated the men, and the real killer confessed to the crimes.

Do I have to be polite when expressing myself about how I feel about these judges for allowing this testimony into their courts? This is not a matter upon which reasonable, educated people might respectfully beg to differ. These are witch trials that have no place in a civil society.

How far does it go? At the Casey Anthony trial a self-styled expert in smells testified that a container of smell– I’m not making this up– from the trunk of Casey Anthony’s car contained the smell of a dead body. Casey Anthony was found not guilty largely because she was able to raise $200,000 for decent lawyers by selling pictures of her with Caylee to People Magazine. Those lawyers successfully challenged a host of junk science evidence.

Now, there are rules about “expert” testimony. Prosecutors interviewed by Frontline didn’t seem aware of them. One of them declared that it was up to the jury to determine whether the smell evidence was truthful, relevant, or accurate. It is not. The Supreme Court has ruled that the judge is the “gatekeeper” for expert testimony and determines whether any specific evidence should be presented or not.

Furthermore, evidence will be deemed qualified if it has been gathered according to a scientific methodology which makes use of valid scientific procedures. One key element is falsifiability.

That said, some judges will permit both sides to present evidence on the scientific validity of certain procedures and expect the jury to sort it out. This gives an enormous advantage to the heavily resourced prosecution in most cases.


My own take on the Caylee Anthony case? I doubt we’ll ever know the truth. Casey Anthony is clearly a disturbed, unstable, delusional young woman, but that doesn’t necessarily mean she is also a murderess. She could be. But we’ve seen enough wrongful convictions to know that people tend to fit the facts to the preferred narrative, not the other way around, and whacky, unstable people are particularly vulnerable.

Here’s the most compelling point in her favor: if the police and prosecutors really believed she was guilty, why on earth did they introduce so much whacky junk forensic science into the proceedings? If you were a prosecutor, wouldn’t you have dumped the “smell” science immediately as something that looked specious and stupid, and would ultimately weaken your case? If you really believed in your own case, with any kind of integrity or intelligence, why would you introduce so many dubious elements into your presentation?

The answer is that prosecutors and police believe that the court system is a bit of a game, and you do what it takes to win, and getting at the truth is merely a secondary objective. I think they see a kind of organic logic to the system, justice theatre, in which their goal is to lock up bad people when something bad happens. If a few innocent people get snagged along the way, so be it.

And if a particular suspect didn’t commit a particular crime but was busted for it anyway– it’s a small price to pay for a system which, they believe, ultimately “works”.



When I was very young, my brother came into our house one day and told me he needed help. He led me to the back of the garage where he had started a fire which was now beginning to lick up the exterior wall. He wanted me to help him put it out. We began filling small plastic buckets with sand from the sand box and throwing it on the wall. In spite of our efforts, the flames grew bigger and bigger, and I believe I was about to tell him we should get real help when I noticed he had disappeared. He had gone back into the house to tell our mom that I had started a fire behind the garage.

I denied it, of course. My mom stared at me and ask me if I was telling the truth. Everybody knows that if you are telling the truth, you won’t get nervous and giggle. I giggled. Busted.

Or maybe I wasn’t. I had a feeling that Mom wasn’t totally convinced. I don’t remember any big punishment other than having to stay in my room for a while.

We now know, I hope, that people giggle when they are nervous, whether they are lying or not. It was the bite mark of my childhood, a wrongful conviction based on spurious evidence. You might think it trivial, but I have never forgotten. I few years ago, I brought it up at a family party and my brother acknowledged that he, in fact, had started the fire. Within a year, the entire family seemed to forget that revelation and went right back to blaming me for it.

, and even to this day my siblings tend to remember that I started that fire rather than the fact that Ed finally admitted the truth years ago.

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