On April 23, 2019, the Supreme Court of the United States heard oral argument in Department of Commerce v. New York, No. 18-966.  The argument focused on three main issues: (1) whether the District Court erred in enjoining the Secretary of the U.S. Department of Commerce from reinstating a question about citizenship to the 2020 decennial census on the ground that the secretary’s decision violated the Administrative Procedure Act, 5 U.S.C. 701 et seq; (2) whether, in an action seeking to set aside agency action under the APA, a district court may order discovery outside the administrative record to probe the mental processes of the agency decisionmaker — including by compelling the testimony of high-ranking executive branch officials — without a strong showing that the decisionmaker disbelieved the objective reasons in the administrative record, irreversibly prejudged the issue, or acted on a legally forbidden basis; and (3) whether the Secretary’s decision to add a citizenship question to the decennial census violated the enumeration clause of the U.S. Constitution.