Google could be forced to change its image search service following a court ruling in the US.
Google argued its use of the images constituted fair use
A federal judge said that the search giant was likely to have violated copyright by displaying small images from the adult magazine Perfect 10.
Google had argued that the thumbnail images constituted fair use.
The case reflects the growing discrepancy between technological change and the legal system, in particular over copyright and fair use.
Perfect 10 (P10) launched its case against Google in November 2004.
It alleged that Google users could find for free its pictures of nude women by providing links to sites containing pirated copies of its images.
The firm publishes a magazine that sells for $7.99 and has a subscription-based website that costs $25.50 per month.
In his ruling, US District Court Judge A. Howard Matz concluded that "Google creation and public display of thumbnails likely do directly infringe P10's copyrights".
"The court reaches this conclusion despite the enormous public benefit that search engines such as Google provide," said the judge in a lengthy court order filed on Friday.
He said that the Google-created thumbnails could undermine Perfect 10's efforts to sell small images to mobile phone users.
However there was some good news for Google. The judge said the search company did not gain financially from the thumbnails.
Instead the websites hosting the pirated images were at fault, meaning that a damages claim against Google was unlikely to succeed.
Judge Matz issued a temporary injunction against Google and gave the two sides until 8 March to work out their differences.
Google has sought to reassure users following the court order.
"We anticipate that any preliminary injunction will have no effect on the vast majority of image searches, and will affect only searches related to Perfect 10," said the company's litigation counsel Michael Kwun said in a statement.
The case highlights issues of copyright in a digital age. Google in particular has faced a barrage of complaints for linking to copyrighted material online via its news aggregator and its book search service.