Slight correction here.
The FPT doctrine makes it so most[0] evidence obtained illegally cannot be admitted. It doesn't work in reverse, it does not imply that all inadmissible evidence is illegal.
For example, the first half of many investigations is full of inadmissible hearsay, before you narrow in on what happened and find the people who actually saw something and can testify. There's nothing wrong with talking to people to figure out who knows things, and see how stories changed when they were told to different people, so you can more fully understand what happened.
How this applies to your main question --
It might be very difficult to use a DNA database company results in a US court because you might have to involve a ton of witnesses to vouch for every part of the process. Suppose the defense asked, "But how do we know the post office didn't mix up different samples that day!?" You would be forced to either (a) have the USPS provide testimony establishing a full chain of custody, or (b) just test the defendant now to verify the match. It will always be easier to do (b), so I'd guess[1] everyone just skips to that step.
[0] Even FPT has exceptions...
[1] Maybe there are other procedural ways to approach this that are more common now, I haven't been involved in cases like these or researched it specifically, my criminal procedure knowledge is getting really dated so I might be wrong here.
> Slight correction here.
> The FPT doctrine makes it so most[0] evidence obtained illegally cannot be admitted. It doesn't work in reverse, it does not imply that all inadmissible evidence is illegal.
> For example, the first half of many investigations is full of inadmissible hearsay, before you narrow in on what happened and find the people who actually saw something and can testify. There's nothing wrong with talking to people to figure out who knows things, and see how stories changed when they were told to different people, so you can more fully understand what happened.
> How this applies to your main question --
> It might be very difficult to use a DNA database company results in a US court because you might have to involve a ton of witnesses to vouch for every part of the process. Suppose the defense asked, "But how do we know the post office didn't mix up different samples that day!?" You would be forced to either (a) have the USPS provide testimony establishing a full chain of custody, or (b) just test the defendant now to verify the match. It will always be easier to do (b), so I'd guess[1] everyone just skips to that step.
I never thought of this but it would be surprising if the USPS _didn't_ maintain some sort of chain of custody of mail items, at least at the bag level or whatever unit they use.
Probably so. And in civil contract law we almost presume the USPS works more or less like a black box and always functions correctly. I mean, more specifically here, you might not have to question the USPS but might have to question the lab techs, or some company representative, and open up debates about what safeguards they use to prevent samples from getting mixed up. Lots of openings you could avoid by just testing on site, so that will always be easier. You generally just do whatever you can to remove extraneous witnesses to simplify your argument.
The subtle trick with US criminal law is that it is still a "testimonial" system. You have to have someone vouch for every piece of evidence. If you take photos of the crime scene you technically have to ask someone questions like, "do these represent the scene of the crime?" ("How would you even know? What makes you an expert on what this place looks like?") Some of this stuff can get waived but in contentious cases you dot your is and cross your ts.
Physical evidence is a bit like a hacked on extension of an old oral only court system. You originally just asked a bunch of villagers what happened and hoped they were sufficiently scared of swearing oaths to not lie.
Maybe something like logistics (i.e., bag went out for delivery on truck FOO) but I doubt they track everyone that has had access to it.
I'm a privacy guy, but the science really is there to use DNA to narrow a list of suspects. You can't say the same for much of forensic science, or for that matter mass surveillance technologies.
https://www.wired.com/story/dna-transfer-framed-murder/
The take-away is that shed skin cells containing DNA can migrate and a DNA match from that type of evidence shouldn't be relied on as proof of anything.
To my view, the combination of DNA transference, advancing DNA collection / analysis techniques, the mere existence of DNA databases, and familial searches are absolutely terrifying.
I do question if society is better off catching a few more criminals through these databases and familial matching vs the potential for innocents to be imprisoned based on nothing more than a DNA match against skin cells.
I'm also not too fond of the idea of my relatives' DNA being used to draw suspicion to another relative just because someone's DNA wound up in a database. To me it's just another one of those things (ALPRs, all the compilations of "it's just metadata") that erode our privacy and give the state a great deal of power for relatively little benefit to the people.
All crimes don't get solved, all criminals don't get caught, and in a society where everyone's a law-breaker because there are too many laws to know them all and so many of them are dumb, that's how things should be.
You investigate someone, hoping to find some law they might have broken.
This is trying to find out who committed an already known serious crime. That's just "police work", in my view.
But once such a suspect is lined up the search is over and all that will happen is to look for confirmation rather than exculpation.
There is nothing special about DNA evidence that makes it worse or better in that regard.