Earlier quoted context omitted.
Yes, the court system exists precisely to determine fuzzy things like this. I'm still curious, what kind of evidence or testimony might be considered believable in this case. Whether someone remembers a particular sequence of words and symbols seems like a thing that's very hard to determine, and by its nature it's unlikely there is any evidence either way. From the quote you give (and I'll admit I have not read up o…
By giving credible oral testimony. The defendant chose not to do that, perhaps because it would have exposed him to cross-examination, and perjury charges if his implausible story was rejected (he remembered other passwords and had been caught with child pornography on other encrypted volumes, and the government may have had evidence about how recently and frequently he had decrypted the external drive, because they…
So the system as it stands is you can be jailed indefinitely because a judge does not believe you actually forgot a password? That doesn't sound ideal.