In 1868, three years after the Civil War ended, the United States ratified the Fourteenth Amendment ^[1]Proposing an amendment to the constitution of the United States., . 14 Stat. 358 (1866). This document can be found in HeinOnline’s U.S. Statutes at Large.—a sweeping constitutional reform aimed at repairing a divided nation. Buried within it was a simple but powerful sentence that would shape generations to come: “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens…”

This sentence is known as the Citizenship Clause, or in more current news it’s referred to as the Birthright Citizenship Clause, and it’s more relevant than ever. As legal challenges surrounding birthright citizenship reach the Supreme Court once again, students and researchers across disciplines—from constitutional law to political science—are revisiting its origin, interpretation, and modern impact.

For law librarians and academic librarians, this moment offers an opportunity to dive into a rich body of historical and legal resources—many of which are available in HeinOnline’s U.S. Supreme Court Library, U.S. Statutes at Large, Civil Rights and Social Justice, Law Journal Library and Legal Classics. This post will help contextualize the Citizenship Clause for research, highlight key primary sources, and provide tools for deeper investigation.

Why the Citizenship Clause Was Created

When the Civil War ended in 1865, it left behind a fractured nation struggling to rebuild. Millions of formerly enslaved people found themselves living in a country where their freedom was recognized, but their legal status and rights remained undefined. Could they own property? Could they vote? Most critically was the question of, were they citizens?

Against this uncertain backdrop, Congress took action and drafted the Fourteenth Amendment. Its purpose was bold and far-reaching: to guarantee equal protection under the law, secure civil rights, and most fundamentally, to provide a clear, national definition of citizenship.

At the heart of this amendment lies the Citizenship Clause, a direct response to one of the most consequential and controversial decisions in Supreme Court history: Dred Scott v. Sandford (1857).^[2]Dred Scott, Plaintiff in Error, v. John F. A. Sandford, 60 U.S. 393, 634 (1856). This document can be found in HeinOnline’s U.S. Supreme Court Library. In that case, the Court held that people of African descent, whether enslaved or free, could never be citizens of the United States. This ruling, rooted in racial exclusion, was one that Congress sought to decisively overturn with the Citizenship Clause.

So, they crafted this sentence:

All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States…

This clause promised a simple, universal standard: if you’re born in the United States, you’re a citizen. No exceptions based on race, ancestry, or lineage. For the first time, citizenship would no longer be left to state discretion or racial qualifications—it became a constitutional right.

💡 Research Tip 💡

Dive into HeinOnline to explore post-war congressional records, commentaries, and articles that discuss the Fourteenth Amendment and constitutional framers like John Bingham, known as the “father of the Fourteenth Amendment.”

Try these searches in HeinOnline:

• “john bingham” AND (“fourteenth amendment” OR citizenship)
• “fourteenth amendment” AND (“citizenship clause” OR “birthright citizenship”)

The Landmark Case that Defined Birthright Citizenship

Fast forward three decades after the ratification of the Fourteenth Amendment. In 1898, the United States was experiencing a period of expansion and tension, including restrictive immigration laws that targeted certain groups—particularly Chinese immigrants. During this time, a pivotal legal challenge made its way to the U.S. Supreme Court: United States v. Wong Kim Ark.^[4]United States v. Wong Kim Ark, 169 U.S. 649, 732 (1898). This document can be found in HeinOnline’s U.S. Supreme Court Library.

Wong Kim Ark was born in San Francisco to Chinese immigrant parents who, under the Chinese Exclusion Act,^[5]To execute certain treaty stipulations relating to Chinese., Chapter 126, 47 Congress, Public Law 47-126. 22 Stat. 58 (1882). This document can be found in HeinOnline’s U.S. Statutes at Large. were legally barred from becoming U.S. citizens. Although Wong had lived his entire life in the U.S., he was denied reentry after a temporary trip abroad on the grounds that he was not a U.S. citizen—despite having been born in California.

The central question before the Court was clear but profound: Does the Citizenship Clause of the Fourteenth Amendment apply to someone born in the United States to foreign nationals who cannot themselves become citizens?

In a 6–2 decision, the Court answered yes. The majority held that the Fourteenth Amendment guarantees birthright citizenship to nearly all individuals born on U.S. soil, regardless of their parents’ citizenship status. This ruling effectively cemented the doctrine of jus soli, or “right of the soil,” into American constitutional law.

The Court reasoned that the language of the Citizenship Clause—“all persons born or naturalized in the United States, and subject to the jurisdiction thereof”—included Wong Kim Ark. The opinion drew on English common law, which had long recognized place of birth as the basis for subjectship and, by extension, citizenship.

This case became the cornerstone for modern interpretations of birthright citizenship and remains central in legal and political debates to this day.

Citizenship in the Modern Era—Why This Matters Now

Fast-forward to today, and the Citizenship Clause is once again in the spotlight. In recent years, questions have surfaced about whether the clause’s guarantees apply to children born in the U.S. to undocumented immigrants, temporary visa holders, or others not granted full legal status.

These questions have been pushed to the forefront by recent Executive Order 14160, Protecting the Meaning and Value of American Citizenship,^[7]90 Fed. Reg. 8449 (2025), Wednesday, January 29, 2025, pages 8327 – 8450. This document can be found in HeinOnline’s Federal Register Library. seeking to redefine birthright citizenship, and by lawsuits such as Trump v. CASA, which challenge long-held interpretations of the Fourteenth Amendment.

While courts are still addressing whether such policies can take effect, these legal battles tap into much larger themes:

• Who decides the meaning of constitutional citizenship?
• Can the executive branch alter that meaning?
• What are the limits of judicial intervention?

This moment offers a rare and powerful opportunity to explore how a single clause in the Constitution connects historical precedent, judicial reasoning, contemporary immigration policy, and public discourse.

Researching the Citizenship Clause in HeinOnline

For researchers looking to explore the Citizenship Clause in depth, HeinOnline provides a solid foundation for examining the Citizenship Clause from multiple disciplinary perspectives. Whether you are researching historical interpretations or analyzing contemporary legal challenges, HeinOnline’s curated databases offer access to primary documents, scholarly commentary, and case law.

Key HeinOnline collections for researching birthright citizenship include:

• U.S. Supreme Court Library: Explore pivotal cases such as United States v. Wong Kim Ark, which established the modern interpretation of birthright citizenship, and decisions shaping Fourteenth Amendment jurisprudence.

• Civil Rights and Social Justice: Delve into documents and commentary related to citizenship, equality, immigration, and constitutional protections.

• Legal Classics: Access 19th-century treatises, congressional speeches, and writings by framers of the Fourteenth Amendment, including John Bingham.

• Law Journal Library: Review peer-reviewed scholarship that examines legal, political, and ethical dimensions of citizenship and immigration policy.

• ABA Preview of U.S. Supreme Court Cases: For current insights, consult the May 2025 issue, which analyzes Trump v. CASA, Inc.—a pending Supreme Court case questioning the scope and enforcement of the Citizenship Clause. The analysis, written by Professor Steven D. Schwinn, provides a clear and balanced overview of the arguments and procedural posture of the case, ideal for those tracking ongoing litigation.

Connecting Legal History to Today’s Debates

Understanding the Citizenship Clause is more than just an academic exercise—it’s a gateway to understanding American identity, legal protections, and the evolution of constitutional rights.

As the nation continues to debate the definition of birthright citizenship, librarians and academic researchers play a vital role in keeping those discussions informed, rigorous, and rooted in fact.

Start your research today in HeinOnline. And for more research support, topic breakdowns, and access tips, don’t forget to subscribe to the HeinOnline Blog—designed for the academic and research community.