Law schools are in turmoil. That is no secret. Yet few people understand that this is, in large part, a crisis of identity. During the first week of January, thousands of members of the Association of American Law Schools gathered to consider “Why Law Matters.” This is the query of a profession trying to remember why it exists.

Memory fails after more than a century spent trying to forget. In 1897, the monumental jurist Oliver Wendell Holmes, Jr., admonished legal educators to wash the “notion of duty . . . with cynical acid” and to study the law strictly from the perspective of the “bad man” who cares only about consequences, while ignoring the good man “who finds his reasons for conduct, whether inside the law or outside of it, in the vaguer sanctions of conscience.”

Since then, law schools in the United States have busily scrubbed the entire edifice of law with legal realism and other corrosive theories. Today, having dismantled common law and its natural law foundations in service to science and equality, legal educators find themselves hard pressed to explain why law should be studied in its own right and not merely as a convenient instrument for social engineering by whichever political party happens to hold power.

Eventually, law professors might again see the attraction of customary law, a real thing grounded in enduring truths. If they come to that realization, they would do very well to read Richard Helmholz’s recent book, Natural Law in Court: A History of Legal Theory in Practice. In it, Helmholz meticulously chronicles the career of natural law in legal education and in practice in Europe and in England between 1500 and 1800, and in the United States from Independence to the Civil War.

Start your day with Public Discourse

Sign up and get our daily essays sent straight to your inbox.

The book is also essential reading for those who love the idea of natural law and are tempted to claim too much efficacy on its behalf, thus damaging its credibility among lawyers. Helmholz’s history bears out both the utility and the context dependence of natural law as employed by lawyers. His study demonstrates “that natural law theory could lead—in fact, did lead—to practical results” in cases in which it was offered in argument. It also reveals that natural law “was open to quite important variations created by the positive law.” Both lessons deserve attention today.

Natural Law Made a Difference

The ius commune of the European continent, the English common law, and the fundamental law of the United States differ in notable respects. But in earlier times they were understood to share a common normative commitment, which is foreign to most law faculties today. Helmholtz explains: “For lawyers educated in those earlier centuries, the dictates of the law of nature were not platitudes. They were not theory. They were living law.”

Natural law did not often conflict dramatically with positive law in those times, and contemporary eyes might for that reason not notice its operation in the historical record. Helmholz notices what others miss because he reads the record on its own terms. In Europe, the “formal sources of law were assumed to stand in harmony with each other. Existing sources in both positive law and natural law were meant to work together toward the attainment of justice.” Similarly, the English common law jurists who exercised a profound influence on American lawyers understood natural law as a means to understand the reasons and intentions of positive law.

Helmholz shows that legal education and practice were both suffused with the law of nature. Natural law has obvious application in the law of the family, growing particularly out of parents’ natural duties toward their biological children. It played an important role in distinguishing those crimes that are criminal by nature from those that are criminal only because prohibited by positive law. Perhaps less obviously to a contemporary reader, natural law was also understood to shape procedure. The summons and notice were justified as requirements of natural law. And though the poor were “hard to summon and harder to listen to with respect,” even those officials charged with administering England’s Poor Law were not excused from giving the poor their due process.

Natural Law is (Partially) Indeterminate

The book also helps to correct a prevalent error. Natural law is often conflated with divine command and other fully determinate moral norms. On the basis of this confusion, it is charged with foreclosing freedom to choose. This charge is closely tied to the suspicion that natural law is a clandestine means to impose moralistic or religious legalism on others through public policy and judicial decisions. But natural law leaves most practical questions underdetermined. Natural law supplies first principles to one’s reason. Human laws are derived from those first principles in more or less direct ways. To equate natural law with rules, commands, or other determinate norms is to miss most of what natural law is and does.

The first principles of natural law entail some rules as a matter of straightforward logical deduction. No just society can tolerate murder or perjury. But most concrete norms must be worked out through a more creative process that Thomas Aquinas called determination. First principles do not alone determine on which side of the road we should drive, or what should be the marginal income tax rate for a married couple filing jointly who earn $122,000 per year.

Natural law does provide some guidance. Everyone must be required to drive on the same side of the road. A couple earning $122,000 per year should not pay less income tax than a couple earning $22,000. Prudential reasons also play a role. For example, in a community with a preexisting custom of driving on the right, a heavy burden of persuasion ought to rest on anyone proposing a law requiring everyone to drive on the left. But within the parameters of what reason will allow and prudence will recommend, there is freedom to choose.

Furthermore, unlike those questions which, for reasons of safety and fairness, must be answered authoritatively the same way for everyone within the political community, most legal judgments are context-dependent and can (and should) vary from case to case. Not every contract must provide the same remedy for breach. Indeed, not all promises must be enforced as contracts. Helmholz observes that natural law came to be criticized as useless where human law more clearly determines the outcomes of cases, such as where law requires consideration for formation of an enforceable contract.

So, natural law does not answer every question the same way for everyone. Nor do the best theorists pretend that it does. Natural law philosophers from Aquinas to John Finnis have affirmed that much (maybe most) human choosing is underdetermined or even undetermined. Moral freedom is not just a matter of choosing between good and evil; it also involves choosing between one good and another good.

So it was when natural law was regularly employed in legal practice. Helmholz has uncovered great variety in the law within the bounds of reason. The purpose of natural law’s condemnation of usury—to prevent exploitation of the poor—is immutable, but statutes allowing moderate rates of interest were upheld in court. Even the religious obligation to pay a tithe was specified by human law. In a case reported by Lord Coke, an ecclesiastical court was denied power to compel collection of tithes of wood because under a local custom the duty to tithe did not apply to wood. Though tithing is required by natural law, “determination of the exact nature of payment nevertheless ‘appertaineth to the law of man to assign.’”

Nor was natural law thought to be the only normative force at work in the law. Helmholz reveals that the application of natural law in earlier centuries was complicated by respect for ancient customs, legislative supremacy, and other jurisprudential commitments. In the ius commune “valid statutes could be displaced by contrary local customs,” while in English common law Parliament was (and is) supreme and it could (can) abolish a custom by stating expressly its intention to do so. Yet even in England, the judicial oath to avoid injustice sometimes required a judge not to read a statute literally, on the understanding that neither the king nor Parliament could have intended to violate natural law.

Natural law operated in the law of the family in subtle and not entirely satisfactory ways. Though natural law was a ground for condemning primogeniture, the practice of passing a decedent’s title to the eldest son, leaving other children without property, by itself it did not abolish primogeniture in England. Nevertheless, it provided an explanation for recognition of local customs forbidding the practice. Natural law also “helped to uphold the validity of conveyances within a family that might not have passed muster if made between strangers.” Yet it was also the foundation for the refusal by English judges to give legal force to adoption, a relation that had to be created by statute.

Famously, common law courts did not abolish slavery out of respect for the duly enacted positive laws of colonies and states that created the peculiar institution. Nevertheless, in cases such as Somerset v. Stewart and Forbes v. Cochrane, courts maintained that slavery had no part in the common law because it is contrary to reason, and therefore held that a slave who set foot on English soil gained irrevocable freedom.

A Foundational Part of the Whole

In the end, Helmholz opines that the “practical limitations” of natural law prevented it from delivering justice. “It did not abolish slavery. It did not end judicial torture.” He concludes that natural law “appears not to have lived up to its promise.” Perhaps. But maybe that was a failure not of natural law but of human officials who rejected or ignored it.

Also, we must consider that natural law did end the slavery of particular persons who managed to get onto English soil and English warships. In later American decisions, such as Buckner v. Street, it provided the justification for refusing to compensate slave owners and dealers whose titles and contracts were extinguished by the Thirteenth Amendment. And though it did not itself abolish the institution of slavery, it founded the reasoned arguments of those who did, such as William Wilberforce and Abraham Lincoln. Those are real accomplishments.

Those who wish to know both the promise and the limitations of natural law should study it by itself and in context, as part of the great civilian and Anglo-American common law traditions in which it plays a foundational role. Natural Law in Court belongs on the natural lawyer’s bookshelf alongside Aquinas and other theorists. Helmholz expertly contextualizes natural law in legal education and practice.

The book also belongs on the desks of law professors. It suggests that the edifice that legal educators leveled through the decades-long application of Holmes’s cynical acid is worth rebuilding. That should be the mission of a profession in search of its identity.