I recently posted a draft article on the Fifth Amendment and compelled entering of passwords: Compelled Decryption and the Privilege Against Self-Incrimination. My article flagged but did not answer a closely-related question: What is the burden of proof to show a foregone conclusion when the government compels entering a password?
Coincidentally, the Massachusetts Supreme Judicial Court happened to invite amicus briefs on this issue in a pending case shortly after I posted my draft. It's a question of first impression among state supreme courts and federal circuit courts, and it relates closely to the underlying Fifth Amendment standard. In for a penny, in for a pound, I say. So today I submitted an amicus brief on the proper burden of proof in compelled decryption cases.
You can read my brief here: Amicus Brief of Professor Orin Kerr on Standards for Compelled Decryption Under the Fifth Amendment. It argues that the government's burden should be to prove by clear and convincing evidence, based on a totality of the circumstances, that the subject of the order knows the password.