While hyperlinking among webpages is an intrinsic feature of the web, some websites object to being linked by other websites; some have claimed that linking to them is not allowed without permission.
Contentious in particular are deep links, which do not point to a site's home page or other entry point designated by the site owner, but to content elsewhere, allowing the user to bypass the site's own designated flow, and inline links, which incorporate the content in question into the pages of the linking site, making it seem part of the linking site's own content unless an explicit attribution is added.
In certain jurisdictions it is or has been held that hyperlinks are not merely references or citations, but are devices for copying web pages. In the Netherlands, Karin Spaink was initially convicted in this way of copyright infringement by linking, although this ruling was overturned in 2003. The courts that advocate this view see the mere publication of a hyperlink that connects to illegal material to be an illegal act in itself, regardless of whether referencing illegal material is illegal. In 2004, Josephine Ho was acquitted of 'hyperlinks that corrupt traditional values' in Taiwan.
In 2000 British Telecom sued Prodigy, claiming that Prodigy infringed its patent (U.S. Patent 4,873,662) on web hyperlinks. After litigation, a court found for Prodigy, ruling that British Telecom's patent did not cover web hyperlinks.
In United States jurisprudence, there is a distinction between the mere act of linking to someone else's website, and linking to content that is illegal (i.e. gambling illegal in the US) or infringing (i.e. illegal MP3 copies). Several courts have found that merely linking to someone else's website, even if by bypassing commercial advertising, is not copyright or trademark infringement, regardless of how much someone else might object. Linking to illegal or infringing content can be sufficiently problematic to give rise to legal liability.For a summary of the current status of US copyright law as to hyperlinking, see discussion regarding the Arriba Soft case.