> It’s obvious that the police will want a device that produces more convictions
If a defendant ever challenges the use of the device, an inaccurate (particularly, false-positive-producing) device is more likely to be thrown out discrediting the device class, not just the individual case, and potentially forcing after-the-fact dismissal of prior convictions.
So, avoidable false-positives isn't necessarily an approach consistent with maximizing convictions.
Unfortunately, it doesn't seem to be that simple in practice; this comment by edmundsato [1] has a lot of good info.
After-the-fact dismissal of convictions may seem like things eventually work out, but remember that in the meantime innocent people's lives are upended as they're thrown into the justice system.
> After-the-fact dismissal of convictions may seem like things eventually work out
No, it doesn't.
But, if the police motivation is maximizing convictions that stick, it's a potentiality that reduces the degree to which a system that produces false positives meets that goal. (Unless you have a system that is as comprehensive a conspiracy as the FBI crime lab wholesale fabrication of the entire field of fiber analysis where essentially all the “experts” in the field were part of the scam...and even that eventually collapsed.)
My point is that before these scams "eventually collapse", people's real lives are caught in the crossfire.
It doesn't even have to be a big conspiracy theory. Here is an instance of a breathalyzer manufacturer pressuring researchers to stop researching whether their devices are faulty [1]. Are they actually delivering false positives? Who knows! We need to bake oversight and accountability in from the jump, not try to back our way in once too many people's lives are disrupted.
> My point is that before these scams "eventually collapse", people's real lives are caught in the crossfire.
Yeah, I’m not disagreeing with that, nor does it seem to disagree with my point, that the consequences of the nearly-inevitable collapse makes it dubious that maximizing positive results by encouraging false positives is actually a means to the proposed police goal of maximizing convictions, if by that one means convictions that stick.
I never suggested, and also explicitly rejected, the idea that this even superficially results in a no-harm situation.
I understand. One point of disagreement that I could have made more clear is that I don't think the collapse is "nearly-inevitable" at all.
I'm also skeptical that it provides sufficient motivation to spend the money to bring the false positive rate down to X acceptable level. This is a for-profit company; they're going to try to get the lowest ratio of R&D spend to revenue that they can.
If a defendant ever challenges the use of the device, an inaccurate (particularly, false-positive-producing) device is more likely to be thrown out discrediting the device class, not just the individual case, and potentially forcing after-the-fact dismissal of prior convictions.
So, avoidable false-positives isn't necessarily an approach consistent with maximizing convictions.