Switching sides, kinda: OK, so you might not be able to assign much culpability to any given data block, so just assign culpability to sharing the metadata that

Switching sides, kinda: OK, so you might not be able to assign much culpability to any given data block, so just assign culpability to sharing the metadata that A⊕B⇒C, right? It's my understanding that that metadata is stored in a "descriptor block" stored in to the network like any other data block (but isn't combined with a set of random other blocks already on the network). I am unsure what the format of that data is, it might very well be easy to identify a block as being a descriptor block (or maybe not, I have no idea). Going after those who download the descriptor block is problematic for the same reasons--that block will end up being reused for other files, the same as any other data block; they could be using it for any number of purposes. OK, so you go after those that say "hey, use this X descriptor block to get such-and-such copyrighted file". Well, there's a reasonable amount of precedent that that sharing a link to a copyrighted work doesn't constitute infringement in many jurisdictions (e.g. hosting a torrent file or a magnet link isn't infringing; it's actually seeding or leaching the contents of the torrent that's infringing). OK, so you go after those that downloaded the descriptor block, then shortly afterward downloaded the data blocks referred to by the descriptor block, and that's reasonable suspicion. Well (1) tracking that is a lot harder than tracking who downloaded an individual block, and (2) there's still a sliver of plausible deniability, so then then you get a subpoena to search their computer for C. Again, the whole point is to make it really _hard_ to tell who's doing what.