Is DOXing someone illegal?

[gideon]

I want to know if DOXing (personally identifiable information usually through using sources like Google and Facebook, etc.) is illegal. A couple of people I know have been DOXed online by someone who wants their website taken down, and they have no idea how to stop it. Is it punishable by law?

[emek]

The law is strange sometimes, but I don't see how it can be illegal to use publicly accessible information published in good faith.
Using stolen credentials to login to private pages on the other hand would be illegal most places (e.g. accessing private Facebook pages without authorization, even if you got the password off some public hacker site)