I.e there is a large directory of PDF files and the publisher makes them available on his website. He does not charge for them and they are available without any requirements for authentication either. Just open the website and browse to your required PDF. I want to build a website compiling many such websites and provide a unified access to these PDFs, could that face any legal complications?
Note: The publishers mainly profit from the website by means of advertisements placed on the site, not on the PDF.