There was a US case discussed in a similar thread a year or two ago (and I
think it was on this list, although it may have been on cypherpunks) where
the issue was a safe combination, and the power of the court to hold a
person in contempt until the safe was opened.
Be prepared to destroy the key, then.
See, in spirit, Boneh&Lipton's paper on revocable backups
http://theory.stanford.edu/~dabo/abstracts/backups.html
http://www.usenix.org/publications/library/proceedings/sec96/boneh.html
Froomkin's and Sergienko's analyses, cited here previously,
are compelling, of course. Unless I missed it in these
two cites, however, there is an open question of whether
deleting a key amounts to destroying evidence as, to this
layman, it ain't evidence until it is admitted. (Why am
I recalling Geraldo's opening Al Capone's vault?...)
--dan
