Yes, they would put you in jail, but more for being a bad liar than for having a faulty memory.
Honestly, if I have a 32 character master-password on a strip of paper in my wallet and I just happen to lose my wallet before I get raided, then I'm pretty sure that I could show that I simply don't know the key.
Because realistically would you write down the pass key in only one place? That's all of your data after all. Your livelihood if you're a developer etc. You may get asked what sort of things losing that password has cost you, if you're the sort of person who has that level of security that probably means you're locked out of all sorts of other systems (thanks to now not having access to private keys) so they can be subpoenaed to see if you've managed to log into your hosting account recently despite not having the private key to do so. And if you magically have preserved your private keys elsewhere why should you be believed that your passkey solely exists on a piece of paper in your wallet...
What about your friends, co-workers etc who might be compelled to testify as to having seen you work on your computer and have never seen you get your wallet out at any point.
And as soon as that isn't believed all other testimony you may give is tainted because you've just lied to the court. Good luck with any mitigation in the event of a guilty plea as well because you've demonstrated you haven't acted in good faith.
They often work hard to find workarounds or ways to charge you with other things to punish you anyway. The most obvious example is being innocent until proven guilty, and yet there are a lot of cases where the police shot someone to death because they raided the wrong home for example (which is why the tool is called SWATd I believe)