The Dog That Didn't Bark: Eligibility to Serve in Congress and the Original Understanding of the Citizenship Clause
President Donald J. Trump’s 2025 Executive Order purporting to restrict birthright citizenship has prompted new interest in the interpretation of the Fourteenth Amendment’s Citizenship Clause. This Essay analyzes an overlooked source of the original understanding of that Clause: the meaning of “citizen” when determining whether Members-elect are qualified to serve in Congress. The U.S. Constitution requires that every member of Congress be a U.S. citizen and further provides that each House “shall be the judge” of members’ qualifications. Anyone is permitted to challenge a Member-elect’s qualifications to serve, and hundreds of challenges have been brought over U.S. history for a variety of reasons. Accordingly, challenges to Members-elect’s citizenship—as well as the absence of such challenges—shed light on the original understanding of the Citizenship Clause.
Using a variety of archival sources, we have researched the ancestry of all 584 members of the Thirty-ninth (1865–1867), Fortieth (1867–1869), and Forty-first (1869–1871) Congresses, and found more than a dozen whose citizenship would be suspect under President Trump’s interpretation of the Citizenship Clause. Yet no one questioned these members’ citizenship despite the contentious political environment that inspired frequent qualifications challenges on a variety of other grounds. This dog that didn’t bark provides additional evidence that the Trump Administration’s novel interpretation of the Citizenship Clause is inconsistent with the original understanding.
We conclude with an observation based on our long hours of tedious research: Determining the status of immigrants arriving in the early nineteenth century—an era with few immigration records and minimal enforcement of existing state-based restrictions on immigration—is often impossible, and always onerous. The difficulty of the task alone is evidence that no one at the time of ratification could have thought that U.S. citizenship turned on such questions.
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