I am not clear about this issue. If someone provided information on his website and marked it as copyright. So it is copyrighted. But what if same copy is available on more than dozen sites and everyone has marked it Copyright again. Then i think it is pretty easy for thugs to steal this content.. is it now copyrighted? If yes then who can take stand on this issue among dozen of websites? How original content holder will be identified?
If you have not permission of anykind of any content then it is not allowed to display on your website whatever it may be.
This is a good question. Are there lawyers on this forum? My guess is that whoever can prove the original copywrite was theirs would be able to hold it. How to prove that? Well...another good question. Logs would be my guess...or those sites that capture snapshots of pages over time....
You cannot use that content without permission if it's not declared to be used freely on your website.
I am a lawyer, but I am not giving legal advice. What I can say is that a) some people may put "copyright" on their pages when in fact they are not protected by copyright (or at least not the entire page), b) some works may be public domain and therefore not subject to copyright protection, and c) some use may fall under the "fair use" exception to the Copyright Act. Furthermore, the creator of the work (i.e. the copyright holder) may have given permission for the other site owners to use the work. You should also realize that not everything in a created work might be copyright-able. Based on my understanding of copyright law (I have limited experience in this field) one cannot copyright facts, but one can copyright the expression by which those facts are presented. For example, a person may be able to borrow dates, names, etc. from the copyrighted site of another without violating the copyright; a violation might occur, however, if that person took straight paragraphs from the site of another. Another thing you ought to realize is that there is some wiggle room involved in copyright law that a court would have to settle. What might appear to be a copyright violation to one might be fair use in reality. Once again, do not construe this as legal advice, but rather a generalization of some aspects of copyright law.