In United States v. Sanmina Corp., 5:15-cv-00092, the Northern District of California denied the enforcement of an IRS summons because the memoranda sought are protected by the attorney client privilege and attorney work product doctrine.  The documents were prepared by in-house counsel and given to accountants providing tax advice.  The court also determined that Sanmina did not waive the privilege by producing a report that references the memoranda, or by providing the memoranda to a law firm that provided both legal and non-legal services.