U.S. companies that offer "Ad Networks" in the U.S. have pledged to bar websites trafficking in pirated goods from using their services and to take other steps to fight online copyright infringement. Eight companies operating online ad networks, including Google, Microsoft, Yahoo and AOL, have agreed to best practices for fighting Internet piracy, they announced Monday.

Ad Networks do not control the content on third-party websites and are not able to remove websites from the Internet. Nor can Ad Networks engage in extensive or definitive fact finding to determine a particular party's intellectual property rights. Nevertheless, the companies believe it is useful for Ad Networks to maintain policies intended to discourage or prevent, to the extent possible, websites that are principally dedicated to selling counterfeit goods or engaging in copyright piracy and have no substantial non-infringing uses from participating in the Ad Network.

The ad networks will prohibit websites "principally dedicated to selling counterfeit goods or engaging in copyright piracy" from advertising with them, according to the best practices. The networks will also allow copyright owners to file complaints about piracy websites running ads, in a process reminiscent of copyright takedown notices under the Digital Millennium Copyright Act.

U.S. President Barack Obama's administration "strongly supports voluntary efforts by the private sector to reduce infringement and we welcome the initiative brought forward by the companies to establish industry-wide standards to combat online piracy and counterfeiting by reducing financial incentives associated with infringement," Victoria Espinel, the U.S. intellectual property enforcement coordinator, wrote in a blog post.

The Recording Industry Association of America and the Motion Picture Association of America both praised the agreement.