Apple has been found guilty of conspiring with five publishers to raise the prices of e-books to compete against Amazon and challenge its dominance of the market.
The three-week non-jury trial began in New York in June in which the US Department of Justice (DoJ) charged Apple with conspiring with publishers to adopt the so-called agency model.
Switching to the model meant that publishers set the price of e-books directly, effectively ending Amazon’s ability to set its own prices.
The five publishers were originally named as defendants alongside Apple, but have already reached settlements.
Penguin settled its case for $75m and Macmillan settled for $26m, while Hachette, HarperCollins and Simon & Schuster created a $69m fund for refunds to consumers.
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New York judge Denise Cote found that Apple had played a central role in facilitating and executing the conspiracy and ordered a new hearing to set damages to be imposed on Apple, according to the BBC.
US Assistant Attorney General Bill Baer called the ruling "a victory for millions of consumers who choose to read books electronically".
But Apple maintains that it brought innovation and competition to the market without restricting it and said it plans to appeal against the rule and continue its fight against “false allegations”.
If Apple fails to get the ruling overturned, the company could face a separate trial by state attorney generals and consumers pursuing class actions and seeking monetary damages.
Apple last year settled an e-book price-fixing antitrust case with the European Commission.