I mentioned this a few years ago and will mention it again. This is how to legitimately say that you can't decrypt your files, even though actually you can. If your laptop is seized and they want you to decrypt the TrueCrypt drive for them, do the following. (Yes, I know TrueCrypt is no longer supported; assume you're using the next-to-last version before they pulled it from the market.)
Agent: "What's this encrypted drive?"
You: "It's for work. It's confidential."
Agent: "Well, decrypt it, please. What's the password?"
You: "It's not just a password, it needs a keyfile."
Agent: "Well, type in the name of the keyfile."
You: "The keyfile's not on this computer. It's on a USB stick."
Agent: "Well, where's the USB stick?"
You: "I'm on vacation, so I didn't bring it with me." (Or, on a business trip: "I'm not working on that project at the moment, so I didn't bring it.")
And everything you say may even be true. So they can still seize your laptop, but good luck to them decrypting it.
However, the secret is this: the keyfile is actually a simple file that you can reproduce from memory. For example, on the actual USB stick, if you choose to actually make one, might be a 1 MB file with random data called "JohnSmith.key"; and also another file called "keyfile.ref", which contains the text "/mnt/media/usb/JohnSmith.key" (or "E:\JohnSmith.key" if more appropriate for your operating system). The secret is that the second file, the tiny one seeming to contain a string that points to the 1MB of gibberish, is itself the keyfile. You might even choose to keep this small file on your laptop drive itself.
In summary, two elements allow this scheme to work: your knowledge of which file is actually the key file, and the plausible denial of your possession of this file because it's supposed to be on detachable storage which you don't have with you.
Maybe if they see that they can't force you to supply a password, they won't "keep in you jail for a while."
Please help refine this by pointing out shortcomings of this scheme.