Diana Erbsen concentrates her practice on federal, state and local tax controversies, including criminal tax matters. She returned to DLA Piper as a partner after serving as the Deputy Assistant Attorney General for Appellate and Review for the Tax Division of the US Department of Justice, a position to which she was appointed by President Barack Obama in 2014 and which she held until the end of the Administration on January 20, 2017.

As one of only two Presidential appointees in the DOJ's Tax Division, Diana oversaw its largest section, the Appellate Section (responsible for all appellate litigation, including to the Supreme Court), as well as the Office of Review (responsible for civil settlements), and the Financial Litigation Unit (tasked with collecting judgments secured by the Trial Sections of the Tax Division). She was also actively involved in the management and operations of the Civil and Criminal Sections of the Tax Division and represented the DOJ on the Advisory Committee on Rules of Bankruptcy Procedure. She was recognized in January 2017 by IRS Chief Counsel William Wilkins with the Chief Counsel Award, the highest honor that can be conferred by that office for her leadership and oversight of the Appellate Section, particularly with respect to cases challenging IRS Regulations and other forms of published guidance. Her contributions to the precedent-setting Altera v. Commissioner case, a model for the government's defense of cases pending in the District Court and the Tax Court, were specifically noted.

Prior to her DOJ appointment, Diana had more than two decades of experience in the tax controversy area (including more than 12 years as a partner at DLA Piper) for which she was recognized by Chambers USA as a Notable Practitioner in the national tax controversy and fraud practice area and by the American College of Tax Counsel as a Fellow.  She has had significant experience representing clients (public and privately held corporations, as well as partnerships, estates and individuals) in all aspects of sophisticated, challenging tax disputes.