A few years ago an overzealous prosecutor put a Massachusetts man in prison for life after a high speed chase. He got the jury to call it murder when it was clearly negligent homicide or manslaughter. While that case was making its way through the system a more sympathetic jury on the other side of the state downgraded murder by vehicle to manslaughter.
The killer was angry that her boyfriend was hanging around with a younger woman. Witnesses said she swerved across the road, didn’t try to brake, and hit the other woman head on dragging her under the car. It’s what lawyers call black letter law. If you intentionally run somebody over society can assume you’re trying to kill. Unlike the vast majority of traffic collisions this was no accident.
The jury gave her a break and found her guilty of voluntary manslaughter instead. Voluntary manslaughter means you’re trying to kill somebody, it’s not an accident, but there is a mitigating factor that makes it less than murder. The defense attorney argued heat of passion. In the old days, if you found your wife in bed with another man you could say anything that happened was in the heat of passion and not murder. It’s the best argument you have if they find you holding a smoking gun. Same principle here. We can’t overlook the crime, but we can let you out on parole in a decade or two.
After receiving that bit of mercy from the jury the defendant appealed over the rules of evidence.
The accident reconstruction expert testified there was a shoe scuff in the middle of the road. That placed the defendant out of her lane. How did he know it’s a shoe scuff mark? Because it looks like a shoe scuff mark. He’s seen a lot of them. He talks about them with colleagues. How do his colleagues know? Because they’ve talked to each other about scuff marks. Has anybody done an experiment? No, but we’ve talked about it.
When it comes to skid marks and crush depth there’s a lot of literature. The precise but inaccurate calculations at least have some foundation. Another expert can say the calculations are good or bad. They are more than some guy’s opinion.
This comes up a lot in traffic control. A city engineer may have approved dozens of stop signs but he can’t point to any reason other than he thinks the intersection needs one. His real expertise is solving neighborhood complaints. At one recent traffic committee meeting the accurately titled “director of community development” handled the community complaints and approved some nuisance stop signs simply on his opinion. But he didn’t make the call at a third intersection where he knew safety was at stake, he outsourced that one to an expert who shared the same letters after his name but actually knew what he was doing.
In criminal trials expert testimony needs to be backed by more than circular logic. Scientific testimony needs a scientific foundation. The witness was not an expert in shoe scuff mark identification, no matter how many times he had done it before. He should not have been allowed to give his faux expert opinion.
Once a guilty verdict is in place it takes quite a lot of work to overturn it. Judges like to say you are entitled to a fair trial but not a perfect trial. The appeals court was satisfied that the woman was not convicted on the basis of that unreliable testimony.
Like it’s harder to remove an illegal sign than to keep it off the road in the first place.
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