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Does the act of broadcasting a unique transaction created by an individual result in forfeiture of any copyright claim that individual might otherwise have had on the creation of that transaction data?
Does the act of broadcasting the block of data that a miner (or pool) created result in forfeiture of any copyright claim that the miner (or pool) might otherwise have had on that block of data?
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If you voluntarily choose to broadcast your unique set of data on the open source network, knowing that it'll become part of the public ledger, then, whether or not it's something that can be copyrighted is pretty irrelevant, as no one is breaching your copyrights (you're the one who chose to make it public).
But I have serious doubt whether such data, despite being unique, is something that could be copyrighted, especially when it's strictly related to, derived from and only usable as part of an open source code/software. That's definitely not what IP protection is for.
I would assume that something similar as "Expectation of privacy" (
https://en.wikipedia.org/wiki/Expectation_of_privacy) comes into play. The whole intent of the software is to produce and maintain this public ledger. Trying to lay claim on a specific transaction or block is a ridiculous thing to do and I expect any reasonable to throw that case out immediately together with whoever brought it.
As a thought experiment I cannot come up with any scenario where a court ruling that there is a copyright on such a block would be in any way enforceable. I think that once a block is out there the only way it could be "removed" without breaking the protocol is by orphaning it. If anyone starts a legal case and wins, orphaning would be practically impossible (because it would be prohibitively expensive to orphan a long chain). The only way to "comply" with such a ruling would be to break protocol with (presumably) a hard fork. I don't see how a court would force anyone outside its jurisdiction to go along with that. The only way would be to ban Bitcoin (and the like) outright?