[johnisgood]

What if it was not intended to be legally published, but you still got access to it because they could not protect it well?

Someone I know actually got access to some stuff this way before; got access to a gold mine that was supposed to be private but someone misconfigured the webserver.

[chrismcb]

In the US, once a secret is out, it is no longer a secret. The person who originally disseminated the secret might be punished, but subsequent use wouldn't be. Facts aren't protected by copyright, they are typically just secrets. Your medical history is secret, and protected by law that would punish the person releasing them. But once released there isn't much you can do about it.

[colejohnson66]

Using a somewhat relevant real world analogy: if I go into a house that should’ve been locked (but wasn’t), and I know I don’t have a right to be there, I can’t argue what I did was legal. It’s the same thing with computers: you can’t use[a] data you don’t have a right to use.

[a]: legally use

[triceratops]

What if you see an open door with gold coins inside? Same answer.

The most you can do is inform the owner that their data isn't protected. And even that, unfairly IMO, is legally dicey.