I wonder, though, if your key were a confession to a crime you did actually commit (perhaps you stole a pack of gum) and you cannot be compelled to testify against yourself, how would that turn out?
This has gone both ways so far in cases in the United States[1]. One of the fundamental questions is whether or not you giving up the key is testimonial or not. There is a litany of things which have been held to not be testimonial, and thus not implicated by the 5th amendment, including giving up your saliva, blood, fingerprints, standing in a line up, etc.
The really interesting legal question to me is as neuroscience advances, it is likely in the near future that scientists may be able recover one's key (or other relevant information regarding crime) through studying one's brain by imaging or the use of other sensors. Under current case law there is a really really good argument this would not be testimonial (i.e. it is similar to taking your fingerprints or blood), yet provides the same information they could obtain by compelling your testimony.
Does the 5th Amendment prohibit the government from scanning your brain to obtain information about a crime? I think there is a significant number of judges who would find under current law it does not.
The really interesting legal question to me is as neuroscience advances, it is likely in the near future that scientists may be able recover one's key (or other relevant information regarding crime) through studying one's brain by imaging or the use of other sensors. Under current case law there is a really really good argument this would not be testimonial (i.e. it is similar to taking your fingerprints or blood), yet provides the same information they could obtain by compelling your testimony.
Does the 5th Amendment prohibit the government from scanning your brain to obtain information about a crime? I think there is a significant number of judges who would find under current law it does not.
[1] http://en.wikipedia.org/wiki/Key_disclosure_law#United_State...