(Reuters) The U.S. Supreme Court on Monday declined to hear a challenge by a group of authors who contend that Google's massive effort to scan millions of books for an online library violates copyright law.

The Authors Guild and several individual writers have argued that the project, known as Google Books, illegally deprives them of revenue. The high court left in place an October 2015 ruling by the 2nd U.S. Circuit Court of Appeals in New York in favor of Google.

Google says it will only show snippets of books, to aid readers in finding the books they seek and help the public discover out of print and forgotten texts.

Mary Rasenberger, executive director of The Authors Guild, counters: "Blinded by the public benefit arguments, the Second Circuit ruling tells us that Google, not authors, deserves to profit from the digitization of their books."

She said the ruling, "misunderstood the importance of emerging online markets for books and book excerpts. It failed to comprehend the very real potential harm to authors resulting from its decision. The price of this short-term public benefit may well be the future vitality of American culture."