I'm confused. If I host someone's copyrighted data, I need the copyright holder's permission.
If I link to the data owner's website, I'm just telling people where the information is to be found.
If I deeplink to the copyright holder's website or link to information they do not want made public then they have only to set up the server to not allow direct access to the data or to password protect sensitive data.
If it is unlawful to direct people to copyrighted data or or look at at without the copyright holder's permission then librarians are criminals. Excuse me, I'm off to post some sensitive copyrighted information on a billboard so that I can sue the lot of you.