SAN JOSE — As lawyers for Google Inc. fought to dismiss a spate of privacy claims, U.S. District Judge Lucy Koh pressed them to explain how scanning messages sent through Gmail to target advertisements falls under the company's "ordinary course of business" as an email provider.

Google lawyers urged Koh on Thursday to dispense with multi-district litigation that accuses the company of mining personal data from emails without users' consent, violating the federal Electronic Communications Privacy Act and a handful of state privacy laws.