SAN FRANCISCO — A federal judge has refused to allow Google Inc. to suspend a privacy class action over email scanning with a mid-stream appeal.

In a seven-page order issued Monday evening, U.S. District Judge Lucy Koh of the Northern District of California declined to certify for interlocutory review her order rejecting Google’s main defenses to multidistrict litigation challenging the company’s practice of scanning Gmail messages to help sell ads. Ruling in September, Koh allowed plaintiffs to move forward with claims the automatic scanning violates wiretap laws.