The Supreme Court declined to hear a challenge from the Authors Guild over their copyright battle with Google Books. (Jhaan Elker/The Washington Post)

The decade-long legal fight over Google's effort to create a digital library of millions of books is finally over.

The Supreme Court on Monday declined to hear a challenge from authors who had argued that the tech giant's project was "brazen violation of copyright law" -- effectively ending the legal battle in Google's favor.

Without the Supreme Court taking up the case, a federal appeals court ruling from October, which found that the book-scanning program fell under the umbrella of fair use, will stand.

Back in 2004, Google started scanning millions of books from major research libraries -- creating a vast database from the digitized copies known as Google Books. Users can search Google Books for quotes or keywords, and it will display paragraphs or pages of context for the results from within the books.

The Authors Guild started complaining about the project in 2005, arguing that Google Books had undermined writers by putting their work online for free.

Google and the Guild worked out a settlement at one point, but it was rejected by a district court judge in 2011. When the case reached the U.S. Court of Appeals for the 2nd Circuit last year, a panel of three judges sided with Google -- finding that the tech giant's efforts amounted to a "transformative" use of the material and that snippets from searching the database don't amount to a "substantial substitute" for an original book.

The Authors Guild then asked the Supreme Court to review the decision -- a request that was denied Monday.

“Today authors suffered a colossal loss,” Authors Guild President Roxana Robinson said in a statement about the high court's decision. Other groups, including the Copyright Alliance, also expressed disappointment at the decision.

"In declining to take the case, the Supreme Court let stand a Second Circuit decision that dramatically expands the boundaries of the fair use doctrine’s transformative use test, which affects creators and copyright owners of all types," Copyright Alliance chief executive Keith Kupferschmid said in a statement.

Google, which had filed a brief opposing the guild's appeal, praised the court's decision to pass on the case.

"We are grateful that the court has agreed to uphold the decision of the Second Circuit, which concluded that Google Books is transformative and consistent with copyright law," the company said in a statement. "The product acts like a card catalog for the digital age by giving people a new way to find and buy books while at the same time advancing the interests of authors."