The legal apparatus you identify is based on the 5th amendment, interpreted through the lens of mythological, historical ideas of how "thought" is different fro

The legal apparatus you identify is based on the 5th amendment, interpreted through the lens of mythological, historical ideas of how "thought" is different from information recorded external to the brain. If you think things are confusing now, wait until merely sticking electrodes on someone's head and making them think about certain things by talking to them, without requiring any voluntary response, can generate usable evidence. Requiring someone to reveal a passphrase or access procedure to reveal encrypted or otherwise secured evidence, external to the brain, is the tip of the iceberg.