No-one disputes that the poster was based on AP's photograph
The Associated Press (AP) news agency says it has counter-sued an artist over his iconic image of Barack Obama.
The red, white and blue portrait by Shepard Fairey appeared on thousands of posters and T-shirts and is now in Washington's National Portrait Gallery.
Its uncredited, uncompensated use of an AP photo violated copyright laws, AP said in a lawsuit filed in New York.
Mr Fairey's lawyer had earlier said it was a case of "fair use", which allows exceptions to copyright law.
The Los Angeles-based street artist has acknowledged that the image - entitled Obama Hope and Obama Progress - is based on a photograph taken in April 2006 by Mannie Garcia, a photographer on assignment for AP.
Mr Fairey knowingly "misappropriated the AP's rights in that image", AP said in a lawsuit filed at a Manhattan federal court, in which it requests that the court award AP profits made from the image and damages.
FAIR USE IN US LAW - KEY QUESTIONS
Purpose of the use: was the image used in a commercial or non-commercial way?
Nature of the copyrighted material: how creative or factual was the original?
Transformation of the work: was the original changed giving it new meaning or value?
Amount copied: how much of the original was copied and was it central to the original?
Effect on the market of the original: could it supplant demand for the original?
"While [Mr Fairey and the companies] have attempted to cloak their actions in the guise of politics and art, there is no doubt that they are profiting handsomely from their misappropriation," the lawsuit says.
Mr Fairey's lawyer, Anthony Falzone, had said earlier: "Fair use protects Shepard's right to do what he did here."
Fair use can, under certain circumstances, give the public a right to copy an author's work for the purpose of criticism, parody, or educational use without permission.
Georgetown University law professor Rebecca Tushnet earlier told the BBC that while Mr Fairey clearly copied the photograph, it could be argued that what he took from it was the basic fact of Mr Obama's features, which do not have a copyright.
"If the case were to go to court, the creative elements of the photograph would have to be established in the first place," she said.
"There's a lot of transformation going on in Mr Fairey's image, and the photograph was pretty factual, so it could prove tricky for AP."