This is something we address during voir dire, when we are picking a jury and wanting to make sure they give both sides a fair shake.
In the DA's office it's known as "the CSI effect."
Not that we don't love TV, of course, we're addicted as the rest of the world. But some shows do cause us concern. The CSI series being one of them.
Here's what happens: intelligent, educated jurors watch numerous cop shows in which a murder, or some other major crime, is committed, solved, and tried in the space of an hour. For that to happen, certain liberties must be taken. The primary liberty is with the investigative technique most open to manipulation: forensics.
I mean, think about it. Detective Smartypants walks up to the chief suspect and drawls, "Listen pal, we know you did it. You had a motive and we ain't got no evidence."
The suspect replies: "Yep, you got me. I did it, and here's how."
Now, that might have flown in the old days when criminals were more honest, but not any more. Nowadays, on TV and in real life, law enforcement has to come up with some evidence. And we both use the wonders of modern science to do it.
But on the CSI shows, here's what happens: A car is tested for DNA. Yes, the whole thing. Or a bathtub (full) is dusted for fingerprints. Facial recognition software scans a metro station video and comes up the guilty perp. Then, to make sure, four days after the shooting the crime scene guru swabs the bad guy's hands for gun shot residue. Machines in the high-tech police station whirr and go "bleep" as NASA-style panels of lights flicker and flash. The good guys gather around the space-age printer with baited breath until the machine chugs out a clear picture of the bad guy. It's really quite beautiful.
And very unreal.
The average juror, of course, can't know quite how unreal. They know you can't get fingerprints from water, of course. But they don't know that it takes months for a DNA analysis. And their expectations are high high high.
I was asked, after a DWI case, why APD hadn't taken fingerprints from the steering wheel to prove who was the driver. After all, the juror was correct that one element of that crime was proving that the defendant (as opposed to someone else) was actually driving. Thing is, who was behind the wheel when the cop pulled him over? Who can you see on the police video climbing out of the driver's side of the car?
In my arson case, which I keep promising to blog about, one of the jurors asked why we didn't have fingerprints from the crime scene. In fact, the defense lawyer made a deal of that issue in closing argument. Fingerprints. From a house that was torched, burned to a crisp. Really?
We do the best we can, so do the cops and scientists. We try to provide every piece of scientific evidence possible, where necessary anyway. But we do like to make sure that everyone's expectations are realistic and that the only burden imposed on us by law, to prove our case beyond a reasonable doubt, is the burden we are held to. And if the forensics help us exceed that burden, so much the better.
PS: In Fort Worth, this new exhibit lets you see how it's done. Looks interesting, I'd love to know how real it is, but kudos to them for expanding the learning experience in this realm.