A New York federal judge on Thursday granted class-action certification to a seven-year-old lawsuit brought against Google Inc. for its efforts to electronically scan millions of books in public and university libraries and make them available online.

The ruling means that individual authors no longer have to sue Google individually over allegations of copyright violation. "The lawsuit now represents all U.S. authors with a copyright interest in the books that Google scanned," said Paul Aiken, executive director of the Authors...