Adduci, Mastriani & Schaumberg LLP

William C. Sjoberg

William C. Sjoberg
t: 202-467-6300
f: 202-466-2006
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  • Customs and International Trade Bar Association (Board of Directors, Treasurer)
  • Georgetown University Law Center (International Trade Update Advisory Board, Co-Chair 2016 Planning Committee)
  • Advisory Committee on Commercial Operations of U.S. Customs and Border Protection (“COAC”) (Working Group on Intellectual Property Rights)
  • Customs Lawyers Association
  • ITC Trial Lawyers Association
  • Washington International Trade Association
  • American Association of Exporters and Importers
  • District of Columbia Bar (International Law Section)
  • State Bar of Texas


  • Texas Tech University School of Law, J.D.
  • University of Texas at Austin, B.B.A., M.A.


  • District of Columbia
  • Texas (Inactive)
  • U.S. Court of Appeals for the Federal Circuit
  • U.S. Court of International Trade

William C. Sjoberg is an international trade and customs attorney with extensive experience practicing before the U.S. Department of Commerce (DOC), U.S. International Trade Commission (ITC), U.S. Department of Homeland Security (DHS), U.S. Department of the Treasury (DOT), U.S. Department of State (DOS), and Office of the United States Trade Representative.

Will's practice focuses on representing clients in antidumping and countervailing duty (AD/CVD) matters before the Office of Enforcement and Compliance (DOC) and the ITC, and on a variety of issues before U.S. Customs and Border Protection (DHS). Will also represents clients in export control matters before the Bureau of Industry and Security (DOC), the Office of Foreign Assets Control (DOT), and the Directorate of Defense Trade Controls (DOS).

Will previously spent five years as an Import Compliance Specialist in the Office of Enforcement and Compliance (formerly the Office of Import Administration), where he was responsible for the qualitative and quantitative analysis of AD/CVD issues.

Prior to entering law school, Will served as a Private Sector Project Manager in investment and export promotion with the United States Agency for International Development in Belize, Central America.

Adduci, Mastriani & Schaumberg, L.L.P. is a Washington D.C. law firm and internationally recognized leader in the field of international trade law with an emphasis on Section 337 intellectual property litigation before the United States International Trade Commission (ITC).  Founded in 1981, the firm has over 30 years of experience practicing before the ITC, all other federal agencies involved in international trade, the United States Court of International Trade, and federal district and appellate courts.  As part of its Section 337 practice, the firm has participated in approximately one-third of all investigations instituted in the last ten years.  In other areas of international trade law, the firm represents clients in antidumping and countervailing duty proceedings, as well as advises clients on Customs valuation and classification, and on country of origin, duty preference programs, sanctions, and export control issues. The firm also advises clients on trade policy issues, including import and export opportunities and barriers, enforcement, and regulatory hurdles.  In addition to its international trade practice, the firm represents clients in a broad range of intellectual property disputes and counsels them on licensing and enforcement.

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