Keys vs. combinations

[T]he law has always drawn a distinction between objects and what’s in your brain. And even though the key to a lock and a series of numbers that’s the combination to a combination lock are functionally the same thing, the law draws a distinction and says that under the Fifth Amendment you can’t be compelled to disclose what’s in your brain if it’s going to hurt you.

Adam Liptak, in conversation with host Bob Garfield on “On the Media”