Earlier quoted context omitted.
Ah yes, but then doesn't the problem boil down to proving that a random value is in fact an encrypted secret? You arrest me, scan my file system and find something named "plan.txt" which is just a bunch of gibberish... what do you do? EDIT: I'll argue that the "main problem" is that as long as real encryption schemes exist, this is impractical to enforce.
In theory, yes that's a big part of the problem. In practice, however, once the gov charges you, you're effectively guilty-until-proven-innocent because your court-appointed public defender is likely not going to be trained or equipped to provide a logical defense, much less hire an expert witness in computer forensics. Plus the gov will approach you with a plea "deal" : you can plead guilty to one charge of illegal…
As someone who likes to be free to use the computers I own, this scares the shit out of me.