The flip side of this is that it becomes impossible for someone to prove that they haven't got an encrypted volume stored somewhere. It will be interesting to see in which way the courts go with this.
To start simply, it's certainly possible to prove that a disk installed with a base install of an OS (and then never touched) contains no encrypted volumes if all of the remaining blocks are empty. Every file can be compared to a known good copy and if there's no other data anywhere on the disk then there can't be anything hidden on it.
From there it's a case of proving that each bit of extra data on this disk relates to a file available under the OS or a fragment of such a file (now deleted). This gets progressively harder the more the disk has been used.
It impossible to deny this when you have a GB+ sized area of unpartitioned data (or unmounted partition) containing seemingly random noise. Or a similar GB+ sized file that you cannot demonstrate to be something benign by unpacking/decrypting/etc. "It's a file of random noise I generated" is going to set off the alarm bells.
Am I wrong or outdated on this?
So in that framework "stored somewhere" is a long ways from "You can characterize the contents of a known drive".