The Motion Picture Association of America (MPAA) has filed suits against Fomdb.com and Movierumor.com, sites which it says facilitate copyright infringement.
"These sites contribute to and profit from massive copyright infringement by identifying, posting, organizing, and indexing links to infringing content found on the Internet that consumers can then view on-demand," said an MPAA statement.
The organisation has filed two civil suits asking for damages and injunctions against the sites under the US Copyright Act of 1976.
"There are many people operating illegal websites like these who are profiting from the theft of protected content," said John Malcolm, director of anti-piracy operations for the MPAA. "We have filed several other similar lawsuits and will continue to do so in order to hold operators accountable for their illegal activities. We have every intention of shutting down these, and sites like them, for good."
The MPAA won two US cases earlier this year over the posting of links to pirated content. It won a $2.7 million judgment against Showstash and a $1.3m judgment against Cinematube in May of this year.
The ruling in the Cinematube case said: "Defendant has engaged in contributory copyright infringement and inducement of copyright infringement by actively searching for, identifying, collecting, posting, organizing, indexing, and posting on his website (www.cinematube.net) links to infringing material, which has been posted on thirdparty websites".
Controversy has surrounded attempts to make website responsible for linking to, rather than directly hosting or disseminating, material.
A man was arrested in October last year in the UK for running a website which linked to copies of old television programmes.
The Federation Against Copyright Theft released a statement at the time claiming that he was arrested for offences related to the "facilitation of copyright infringement", while the police said that it was for "supplying property with a registered trade mark without permission".
The first of these is not an offence and the second does not fit the circumstances, according to Kim Walker, head of intellectual property at Pinsent Masons, the law firm behind OUT-LAW.COM.
"We don't have an offence in the UK for facilitation of copyright infringement," said Walker at the time. "Instead, it is possible that prosecutors could attempt to characterise this as an offence of 'distributing' infringing copies or 'communicating' copies to the public in the course of a business."
"If TV Links carried advertising, it's arguably a business. If it didn't carry advertising, it can still be criminal if the site can be shown to affect the copyright owner in a prejudicial way," he said.
A French court ruled earlier this year that a site which linked to material had the same liability as the site which hosted the material.
In a case involving Kylie Minogue's ex-boyfriend Olivier Martinez, the courts said that sites which linked to articles which illegally invaded his privacy shared responsibility for that invasion.
