SAN FRANCISCO — It’s legal under copyright law for Google to scan millions of books and make snippets of them searchable online, a U.S. appeals court ruled Friday.

The ruling is part of a  decade-long, bitter battle between authors and publishers on one side and researchers and Google on the other.

Google, whose parent company is  known as Alphabet, began its book-scanning project in 2004. The scanned volumes are searchable online but only in snippets.

Google’s argument has been those snippets are legal under the “fair use” provisions of U.S. copyright law, which allows limited use of copyrighted material without the permission of the rights’ holders. It’s the same legal use that allows reviewers to quote from books without paying for the privilege.

The Authors Guild and several individual writers sued Google in 2005, arguing Google’s scans illegally deprived them of revenue from their writings.

Google responded to author complaints by saying the ability to search books would not harm authors but help them by aiding readers in finding and choosing to buy volumes they might not have otherwise.

Friday, the 2nd U.S. Circuit Court of Appeals in New York unanimously agreed with Google.

“Google’s division of the page into tiny snippets is designed to show the searcher just enough context surrounding the searched term to help her evaluate whether the book falls within the scope of her interest (without revealing so much as to threaten the author’s copyright interests),” Circuit Judge Pierre Leval wrote in the ruling.

In a statement, Google said it was pleased the court has confirmed its digitization project is fair use, acting much like a card catalog for the digital age.

A key element in determining whether something falls under fair use is whether the use is sufficiently “transformative” that it creates a new work without substantially harming the market value for the original work, said J. Michael Keyes, an intellectual property partner at the law firm Dorsey and Whitney.

“The court weighed competing policy and legal considerations to side with Google to find that its scanning and making snippets available for online research was a laudable ‘transformative’ use of the underlying original works,” he said.

Authors Guild Executive Director Mary Rasenberger said she was disappointed the court was “unable to see the damaging effect that uses such as Google’s will have on authors’ potential income.”

She made it clear the Authors Guild planned to appeal the decision.

“We trust that the Supreme Court will see fit to correct the 2nd Circuit’s reduction of fair use to a one-factor test — whether the use is, in the court’s eye, ‘transformative,’” she said.

Follow USA TODAY tech reporter Elizabeth Weise on Twitter:@eweise

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