I was asked about what the copyright issues are with hyperlinks on the web. So, in US law, generally there is no copyright issue with linking because the link causes the person clicking on it to load a copy of the web site, but the person who posts the link is not making a copy, or displaying a copy, or distributing a copy so there's no copyright issue for the person posting the link. (And therefore, there's generally no legal theory that a site can use to stop someone from linking to their site, even if it's a so-called "deep" link or an in-line link). See Perfect 10 v. Amazon, Inc., 487 F.3d 701 (9th Cir. 2007).
The one exception is if the target site has material that infringes copyright on it. In that case, even though the person linking to the site is not directly infringing, they could be liable on the theory of indirect infringement - helping someone else to infringe copyright.
The one law that specifically deals with this is Section 512(d) of the Copyright Act, which creates a "safe harbor" for search engines and others who link to "online locations" with copyright infringing materials. As long as the search engine removes the link after receiving notice of the infringing materials, the search engine does not owe the copyright owner any money.
For more information, see the Chilling Effects site.