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“The goal of search engines, and of products like Google Book Search and YouTube, is to help users find information from content producers of every size,” David Drummond, Google’s chief legal officer, said in a statement in response to Rubin’s speech. “We do this by complying with international copyright laws, and the result has been more exposure and in many cases more revenue for authors, publishers and producers of content.”

Rubin cast Microsoft’s own book search as superior on copyright treatment. Experts didn’t find this a surprising move given that Google, with its recent online word processing and spreadsheet offerings, has begun to encroach on Microsoft’s core software businesses.

Microsoft has reacted to Google’s success in recent years by beefing up its search capabilities, but may wind up harming itself with Rubin’s arguments. After all, a lot of the law is unsettled when it comes to copyright protection in the digital age, said Eric Goldman, director of Santa Clara University School of Law’s High Tech Law Institute

“It’s a very dangerous game for Microsoft to go out and push a major player in this space on copyright issues,” Goldman said. “It’s entirely possible that if they succeed in painting Google into a box, they may have inflicted a wound on themselves.”

Courts are still grappling with whether Google’s approach to books constitutes “fair use” under copyright law, Flagel said. Judges are also weighing whether Google should be held responsible for providing information, in search results for instance, about businesses that infringe on other people’s copyrights.

The Ninth Circuit U.S. Court of Appeals is expected to rule on three related cases on that subject by the end of the summer, said Fred Von Lohmann, a staff attorney for the Electronic Frontier Foundation in San Francisco.

Von Lohmann said Rubin’s speech, which played up the fact that Microsoft asks copyright holders’ permission before using their works, highlighted a way of thinking that he finds highly disturbing. Seeking permission from movie studios and publishing houses before using their material for a new innovation might be something Microsoft � with its resources � can do easily, but small-time innovators can’t, Von Lohmann said.

“If you’re a startup in a garage, is Hollywood going to return your calls if you’re trying to develop something like YouTube?” he said. “Do you think they would have been able to launch a company if they had to negotiate permission?”

He continued: “The question here is not about do you like Google better or Microsoft. The question is, do you want a world where you can innovate first, or you have to hire lawyers and ask Hollywood’s permission.”