Some really good PDF on how this works in Europe, the Netherlands and comparisons to US law. (I took me quite some time to find something looking authoritative enough to actually read.)
"If Alice has stored her key on a diskette
or a smart card, and if Polly is certain of its existence and Alice’s possession of them, she can
summon Alice to deliver it – at least, in the United States she can, and also in European
countries, according to the European Court’s decision in Saunders. In the Netherlands, article
107 paragraph 1 DCCP, however, prohibits Polly from commanding delivery from suspects."
Further on (page 11) goes on to state that a key that doesn't exist in the physical plane might be considered admission, and therefore protected. That is unless it is demonstrated that the suspect used the same key (elsewhere) recently -- in which case it's already "admitted" by the suspect and the s/he needs to deliver the key.
"If Alice has stored her key on a diskette or a smart card, and if Polly is certain of its existence and Alice’s possession of them, she can summon Alice to deliver it – at least, in the United States she can, and also in European countries, according to the European Court’s decision in Saunders. In the Netherlands, article 107 paragraph 1 DCCP, however, prohibits Polly from commanding delivery from suspects."
Further on (page 11) goes on to state that a key that doesn't exist in the physical plane might be considered admission, and therefore protected. That is unless it is demonstrated that the suspect used the same key (elsewhere) recently -- in which case it's already "admitted" by the suspect and the s/he needs to deliver the key.
http://rechten.uvt.nl/koops/THESIS/cryptocontroversy-ch08.PD...