I can't help but feel there's something vital missing from police, DA, etc training. I'm reminded very distinctly of my ethics class (which was required for graduation), where we were told the horror story of the THERAC-25. Even now, when I work on software for the military, I am very conscious of what my decisions may cost. Why aren't police, judges, district attorneys and forensic scientists required to take classes that tell them of stories like this one? I feel that juries aren't enough, especially when they are surrounded by those with much more experience and comfort in the courtroom.
This could be selection bias at work. Perhaps you terminate conversations with less intelligent officers earlier, without realising the reason you do so. So, these less intelligent ones are forgotten, or removed from your sample because the conversation was not long enough to find strong evidence about intelligence.
No. He's just poor at judging intelligence, like everyone else.
If they are polite and don't raise their voice and there are no obvious deficiencies in their vocabulary or pronunciation, and they seem to be minimally informed on current events and trends, you couldn't tell an idiot from a genius. You have no ability to see their thought processes, and you've never really bothered to try to infer them.
Studies even suggest you don't know what's going on in your own brain either. This despite the fact that you are actually privy to at least some of your own thought process.
[citation needed]
The citations will probably be helpful for you to find the studies and similar ones.
My favorites:
Why did we think we dreamed in black and white?
http://www.faculty.ucr.edu/~eschwitz/SchwitzAbs/DreamB&W.htm
How well do we know our own conscious experience? The case of human echolocation.
http://www.faculty.ucr.edu/~eschwitz/SchwitzAbs/Echo.htm
edit: here's an interview - http://www.3ammagazine.com/3am/the-splintered-skeptic/
I think we all want tools that help us do our jobs quickly and more reliably. Forensic science is, in aggregate, a tool for discovering what's true. Improvements in forensic science are, on balance, a net positive.
In the United States, nothing prevents prosecution. The state can bring whatever charges it wants. The bulwarks of our freedom are in the courts, the ballot box, and in the enumerated Bill of Rights.
It's the jury of our peers and a speedy trial that check the ability of prosecutors to do us individual harm. As a society, it's our power at the ballot box that determines who we admit into the job of prosecution.