[bendykstra]

The self-incrimination clause was motivated by the practice of forced confessions, which were elicited by threats, indefinite detention and torture. You can get a DNA sample with a cotton swab, but it takes much worse to extract information from someone's mind.

[smsm42]

It's not only because of the amount of force used. It's also because of the power it gives to the police.

If they had a mental scanner that allowed to get information out of people's brain without keeping them in jail forever or torturing them, it still be a problem - because without controls on it what the police would do is just round up everyone looking suspicious enough, brain-scan them en masse and use all the information gathered. And of course they would claim "if you're a honest man, you don't have a reason to be concerned".

So it's not only about torture & detention, it's about not giving police the power to own any information they'd like to have just because they want it. We have "due process" because police and state power is huge even as it is, without strict controls on it a private citizen has very little chance to resist any abuse and to correct any error.