“Our point of view seemed to have been ignored,” said Oren Teicher, chief executive of the booksellers association. “But the climate has changed. There are efforts in the European Union — in Germany and a few other countries — to take a closer look at Amazon’s practices. That has ramifications on what happens here.”

Last month, the European Union formally announced an antitrust investigation into whether Amazon was stifling competition in e-books by using restrictive contracts with publishers.

Amazon has come an immense distance from its dot-com origins. Yet even as it plunges into Hollywood filmmaking and its cloud computing division outdistances competitors such as Google and Microsoft, sales of books, music and videos in North America are unimpressive. In the most recent quarter, revenue in the segment was up only 5 percent. The book business has become more dependent on Amazon, but it has become almost an afterthought to the company itself.

Looming over the current conflict is the attempt in 2010 by Apple, which was introducing the iPad, and five major publishers to wrest some control of digital books away from Amazon. The publishers feared that Amazon’s pricing policies would put them out of business. At the time, Amazon had 90 percent of the e-book market.

The gambit backfired. Federal prosecutors took Amazon’s view that this was collusion to impose higher prices — an action harmful to consumers and by definition illegal.

Apple and the publishers argued that whatever the short-term effect on consumers, the entry of another major participant would provide more competition and thus benefit consumers in the long term.

The publishers settled the case. Apple lost at trial and lost again last month on appeal.

Judge Raymond J. Lohier Jr. of the United States Court of Appeals for the Second Circuit, concurring with the majority, saw some merit to Apple’s and the publishers’ argument but said that “more corporate bullying is not an appropriate antidote to corporate bullying.”