A Constitutional Argument With Deep Roots – Now Claimed by One Side
For most of American legal history, the argument that the Constitution carries a moral dimension – that its words point toward principles of natural law transcending the written text – belonged to no single political tradition. Abolitionists wielded it to condemn slavery. Civil rights lawyers wielded it to challenge segregation. The idea that certain rights exist prior to and independent of government was, for generations, a tool available to whoever needed it most urgently. What has changed, in the past few decades, is who reaches for it.
Conservatives now hold that tool almost exclusively. From abortion to gun rights to religious liberty, the right has built a jurisprudential project around the claim that the Constitution’s meaning is anchored in something deeper than its literal language – a moral order that courts are obligated to recognize. Liberals, meanwhile, have largely stepped away from that tradition, leaving a rhetorical and philosophical space that their opponents have filled with considerable discipline.
What Natural Law Actually Means in a Legal Context
Natural law, as a jurisprudential concept, holds that there are moral truths accessible through reason that law must reflect to be legitimate. It is not a religious doctrine, though religious thinkers have developed it extensively – it predates Christianity in Western philosophy and runs through Cicero, Aquinas, Locke, and into the founding generation’s debates about what kind of document the Constitution should be. When Thomas Jefferson wrote that certain rights are “unalienable,” he was gesturing at exactly this tradition: rights that governments do not grant and therefore cannot legitimately revoke.
In American courts, natural law thinking has surfaced at moments when the written text of the Constitution offered insufficient guidance, or when the stakes demanded something more than a parsing of clauses. The Fourteenth Amendment’s guarantee of equal protection, read narrowly, might not have compelled the outcome in Brown v. Board of Education. The argument that segregation was not merely unequal but morally wrong – that it violated a deeper conception of human dignity – carried real weight in the thinking that produced that decision. The same logic animated the legal attack on anti-miscegenation laws, on poll taxes, on the systematic exclusion of women from civic life.
The point is that moral readings of the Constitution have historically done progressive work. They provided the intellectual architecture for expanding rights, not contracting them. Which makes the current inversion – conservatives using natural law to limit abortion access, to entrench gun rights, to protect certain religious exercises from anti-discrimination law – a genuinely significant ideological reversal that has received far less attention than it deserves.
Why Liberals Retreated From the Argument
The left’s withdrawal from natural law reasoning did not happen overnight, and it was not entirely irrational. After the Warren Court era, liberal legal thinkers became increasingly concerned about the dangers of unelected judges substituting their moral views for democratically enacted law. The criticism of Lochner v. New York – the 1905 decision in which the Supreme Court struck down a maximum-hours law on the grounds that it violated a judicially invented right to contract – became a foundational cautionary tale. If conservative justices could use natural law thinking to protect economic privilege, the lesson drawn was that moral reasoning by courts was inherently suspect.
That lesson produced a generation of liberal legal scholars who emphasized proceduralism, democratic legitimacy, and the dangers of judicial overreach – arguments that were intellectually coherent but that ceded the moral high ground in a way that would eventually prove costly. When conservatives developed their own sophisticated natural law jurisprudence, centered on originalism and the claim that the Constitution’s moral commitments were fixed at ratification, liberals found themselves without a ready counter-framework. The tools they had set aside were now being used against them.
The Conservative Project and What It Has Built
The conservative legal movement’s success did not arrive by accident. Organizations like the Federalist Society, founded in 1982, created pipelines for a particular style of constitutional thinking – one that combined originalism as a method with natural law as a background philosophy. The argument, developed by thinkers like Robert Bork and later refined by justices including Antonin Scalia and Clarence Thomas, held that the Constitution’s original public meaning was the only legitimate basis for interpretation. But embedded in that claim was always a substantive moral vision: that certain rights were fixed, certain structures were sacred, and that courts had a duty to restore what progressive jurisprudence had distorted.
The practical results of that project are now visible across the legal landscape. The 2022 decision in Dobbs v. Jackson Women’s Health Organization, which overturned Roe v. Wade, was in significant part an argument about which rights have deep enough historical and moral roots to warrant constitutional protection – and the majority concluded that abortion did not qualify. The 2022 decision in New York State Rifle and Pistol Association v. Bruen established that gun regulations must be consistent with the historical tradition of firearm regulation at the founding, effectively enshrining an eighteenth-century moral understanding of armed citizenship as the constitutional baseline. These are not merely textual decisions. They are moral decisions dressed in historical language.
Clarence Thomas has been perhaps the most explicit about the underlying philosophy. In multiple opinions and concurrences, Thomas has argued that the Court should ground its decisions in natural law and the moral framework of the founding era – a framework he argues was itself derived from natural law thinking. His concurrence in Dobbs invited challenges to Griswold v. Connecticut, which protects contraception access, and to Obergefell v. Hodges, which established marriage equality, on the grounds that those rights, like abortion, lack sufficient historical grounding. The invitation was not casual. It was a program.
What makes this moment intellectually strange is that the left once made exactly this kind of argument – that the Constitution’s commitments to liberty and equality point beyond their specific historical applications toward broader moral principles that courts have a duty to recognize and extend. The difference is that liberals used that reasoning expansively, to bring more people within constitutional protection. The current conservative project uses a structurally similar argument to draw the circle tighter.
Whether the Left Can – or Should – Reclaim the Tradition
There are liberal legal scholars who argue that the retreat from moral constitutionalism was a mistake and that the left needs to rebuild a principled account of why the Constitution’s guarantees carry moral weight that transcends their original applications. Yale law professor Jack Balkin has argued for a “living originalism” that takes the original constitutional commitments seriously while recognizing that their application must evolve as moral understanding develops. Harvard’s Laurence Tribe spent decades developing a constitutional theory grounded in moral philosophy before concluding, near the end of his career, that the current Court had made such reasoning nearly impossible to practice.
The difficulty is institutional as much as intellectual. Natural law arguments work when courts are willing to entertain them, and the current Supreme Court, with its six-three conservative majority, has signaled clearly what kind of moral framework it finds persuasive. Liberals arguing for a moral reading of the Constitution that supports expanded rights face a bench that has already decided which moral tradition counts. The argument has to be made anyway – in law schools, in lower courts, in the long project of building a counter-jurisprudence – but the timeline for it to matter at the Supreme Court level is not obviously short.
The history of these shifts offers some cold comfort. The conservative legal movement spent roughly forty years building the intellectual infrastructure that produced the current Court. The abolitionists who invoked natural law to condemn slavery did so for decades before the Thirteenth Amendment made their argument constitutionally irreversible. Legal ideas move slowly, accumulate, and then arrive at the Court in the form of cases where the groundwork has already been laid.
What remains unresolved is whether liberals will attempt to rebuild on moral ground or continue to argue primarily from procedure and democratic legitimacy – a strategy that has not prevented the steady contraction of rights that originalists consider historically unsupported. Somewhere in that choice is the question of what the Constitution is actually for, and who gets to say so.
