[argvargc]

By the same, uh, token, could you find a bunch of commits from a large github repo that each form successive parts of the key, post an issue referencing them, and then make that repo - or even all github - illegal in the USA?

If Bitcoin's primary design and purpose to disseminate bluray decryption keys, and provide unfettered access to them to anybody and everybody, and advertise it as such, there may be some kind of an argument to be made.

But as it's not, and there are hoops to jump through, doesn't it make about as much sense as trying to make malls and permanent markers illegal, because someone wrote a bluray decryption key under a mall toilets cistern lid?

[Beltalowda]

But you can remove that Blu-Ray decryption key from the toilets cistern lid. With the blockchain, that is much harder (or impossible?)

[argvargc]

Sort of. If someone figures out the right UV lamp will reveal remnants of the marker pen, you'll have to make UV lamps illegal. Or if someone took a photo of the key before it was erased and uploaded it, you'll have to make cameras and the internet illegal.

In our present reality, almost every piece of information - with sufficient intent - can effectively become immutable, owing to our interconnectivity and resourcefulness.

And as I understand it this is the part that matters legally - the law is concerned with that intent.

I often see people claiming an immutable blockchain and all of its users are potentially in violation of the law because someone put something on it that's illegal and therefore everyone around the world with an unwitting copy of that information is breaking the law. But is that how the law works? (Well, when it's working - which it doesn't always, but in general.)

In this example of someone putting illegal content on the Bitcoin blockchain, the system and its users could be more rightly seen as victims of the crime. Just as much as the mall owner is a victim of an act of vandalism, or the github repo's owner.

None of these parties had the intent to host this information.

However if a particular blockchain was specifically created and marketed as a place to host and get bluray keys, and all peers and miners hosting copies of it clearly knew that, then they are showing intent to break the law and would be treated differently.

Now IANAL, and neither is this a perfect metric and it becomes a grey area at times, but as I understand it, this question of intent is fundamental to law and how it's enforced in the real world.

We can think of countless examples of how doing anything else would result in continual and repeated injustices.

Turning an apartment buildings worth of people into criminals would be as simple as putting a piece of paper with a decryption key on it into everyones letterbox.

No. They're the victims of unsolicited mail. It doesn't mean all of them and the postal system should be considered illegal, even if they unwittingly kept the letter in a stack with other junk mail in their room.