A deal between Apple and publishers to set the price of e-books cost customers "hundreds of millions of dollars", a government lawyer has claimed.
Lawrence Buterman made the claim while speaking at the opening of a trial into price-fixing allegations against the iPad and iPhone maker.
He said a rise in e-book prices after the launch of the iPad in 2010 was the result of a deliberate scheme.
However, Apple's lawyer described the prosecution's case as "bizarre".
Defence lawyer Orin Snyder said the government had "reverse engineered a conspiracy" by linking price rises to Apple's deals with the publishers.
The technology giant has claimed that it acted in its own business interests when it made deals with publishers to supply e-books it sold through its iBooks platform.
Apple encouraged publishers to set the price of their e-books, rather than allowing retailers to decide the price.
Prosecutors say this was aimed at Amazon - a rival e-book retailer that charged lower prices than Apple was able to offer.
They say that, as a result, Amazon's typical price of $9.99 for a best-seller rose to $12.99 or $14.99 after the launch of the iPad.
But Mr Snyder disputed this, and argued that Apple could not be held responsible for the business decisions of others.
The trial, which started in New York on Monday, is expected to last several weeks.
Five publishers have already reached settlements over the case.