Or how about a sort of dead-man's switch? Is that tampering? Everything you did was put into place before you got into trouble. Can you be charged with "pre-tampering" of evidence? Or how about "not untampering" of evidence?

Couldn't I encrypt my private key with a TPM, give them the encrypted private key and have them say insert a smart card that clears the TPM, (or clear it myself) putting the private key beyond reach? Does the TPM manufacturer keep the burned in TPM private key used to encrypt other things (like my key) on record? I have an older TPM not built into my chipset so am not worried about not trusting say Intel