[pjc50]

Legally it's not complicated: is it a copy? Is it permitted by the copyright owner? No? Then it's an infringing copy.

Actually doing something about it is a problem, as shown throughout the post-Napster era, but every node that serves an infringing copy is potentially liable.

[shock-value]

A lot of nodes are run by some (relatively) well-known, well-funded companies. See https://ethereum.org/en/developers/docs/nodes-and-clients/no...

Wonder if they will be or have been subject to copyright complaints / lawsuits.

[MereInterest]

I'd add a number of additional complications.

* Is the material copyrightable? A novel is copyrightable, but a recipe is not. The layout format of a telephone book is copyrightable, but the contents of it are not.

* Is the copyright still in effect? Unfortunately, this is a less relevant question now, as anything written within living memory is under copyright, but it is still a required step.

* Is permission from the copyright holder required? If I am sold a copy of a computer program, I'm allowed to make whatever copies are necessary (e.g. copying from the hard drive to RAM) that are necessary to execute the program, without the permission of the copyright holder.

* What is being done with the copy? If I buy a work, the copyright owner has no right to prevent me from selling it, nor are they entitled to any portion of the proceeds. Re-sale of authorized copies, regardless of permission, are not infringements.