The U.S. Supreme Court case Department of Commerce v. New York, 2018, centered around the Trump administration's attempt to add a citizenship question to the 2020 census questionnaire. The state of New York and other plaintiffs argued that this addition was politically motivated and would result in an undercounting of immigrant communities, thus violating the Enumeration Clause of the Constitution which requires an accurate count for congressional representation purposes. The Department of Commerce contended that it had discretion over census questions and that citizenship data was necessary for enforcing voting rights laws. In June 2019, in a complex decision with multiple opinions written by different justices, the Supreme Court ruled against adding the question on procedural grounds without definitively resolving constitutional issues raised by plaintiffs or completely barring future attempts to include such a question.

In the dissenting opinion for the Department of Commerce v. New York case, Justice Clarence Thomas, joined by Justices Neil Gorsuch and Brett Kavanaugh, argued that the decision to reinstate a citizenship question on the 2020 Census was within Secretary Ross's discretion under current law and should not be subjected to judicial review. They contended that there is historical precedent for such questions in census surveys and criticized what they saw as an overreach by courts into executive matters. The justices also disagreed with claims that adding this question would lead to less accurate data due to non-response or false answers from certain populations fearing potential misuse of their information. They maintained it was speculative at best whether these fears were justified or if any negative impact would occur.