The Nuremberg Code is a set of ten ethical principles governing human experimentation, born out of the war crimes tribunal that prosecuted Nazi doctors after World War II. Issued in 1947 as part of the judges’ verdict in what became known as the Doctors’ Trial, it was the first international document to insist that no medical experiment could be performed on a person without their voluntary, informed consent. The Code was never a statute passed by a legislature, yet its principles rippled outward through decades of international law, medical ethics, and research regulation in ways that still shape how clinical trials are designed and reviewed today.
The Doctors’ Trial
Between December 1946 and August 1947, twenty-three German physicians and medical scientists stood trial before an American military tribunal in Nuremberg, Germany. The charges were murder and torture carried out through medical experiments on concentration camp prisoners. The experiments were gruesome: subjects were submerged in freezing water, locked in low-pressure chambers to simulate high altitude, deliberately infected with malaria and typhus, and forced to drink seawater for days. Many died. Many more were permanently disabled.
The defendants were not obscure figures. They were respected scientists and physicians, some holding prominent academic or government positions. The prosecution’s medical case leaned heavily on the testimony of two American doctors, Leopold Alexander and Andrew Ivy, along with a German physician named Werner Leibbrandt, all of whom identified themselves as Hippocratic physicians sworn to “do no harm.”1PubMed Central. American Doctors at the Nuremberg Medical Trial At trial’s end, seven defendants were acquitted, seven received death sentences, and the remainder received prison terms ranging from ten years to life. Alongside the verdict, the judges articulated ten principles they considered necessary for any ethical human experiment. That list became the Nuremberg Code.
Who Actually Wrote the Code
Authorship of the Nuremberg Code has been disputed almost since the day it appeared. The ten principles were formally enunciated by the judges, particularly Judge Harold Sebring, as part of the tribunal’s written opinion. But the intellectual content drew on memoranda prepared by the prosecution’s expert witnesses. During the trial, both Dr. Andrew Ivy and Dr. Leo Alexander submitted detailed proposals outlining the conditions under which human experimentation could be ethically justified. After the verdict, both men claimed sole authorship of the Code’s substance.2PubMed. Leo Alexander’s Blueprint of the Nuremberg Code
Alexander had drafted a six-point memorandum early in the trial that covered consent, proper scientific design, and the duty to protect subjects from unnecessary harm. Ivy independently produced his own set of principles. The judges appear to have synthesized both contributions, expanding and reorganizing the material into the final ten-point list. So the honest answer is that the Code had multiple authors: Alexander and Ivy shaped the substance, and the judges shaped the final text and gave it legal weight through the verdict. Neither man can fairly claim exclusive credit.
The Ten Principles
The Code’s principles can be grouped loosely into three concerns: the rights of the person being experimented on, the scientific justification for the experiment, and the responsibilities of the researcher conducting it. Here they are in plain language:
- Voluntary consent: The person must freely agree to participate. They must be legally capable of giving consent, must not be coerced or deceived, and must understand what the experiment involves well enough to make a genuine decision.
- Necessary and fruitful: The experiment must aim to produce results that benefit society and that cannot be obtained by other means.
- Based on prior evidence: The experiment should be designed on the basis of earlier animal studies and existing knowledge of the disease or problem, so that the expected results justify performing the experiment on humans.
- Avoid unnecessary suffering: All unnecessary physical and mental suffering and injury must be avoided.
- No expectation of death or disabling injury: No experiment should be conducted if there is reason to believe it will cause death or a disabling injury. The only exception is when the researchers themselves serve as subjects.
- Risk must not exceed benefit: The degree of risk must never exceed the humanitarian importance of the problem the experiment is designed to solve.
- Proper protections: Adequate preparations and proper facilities must be in place to protect the subject against even remote possibilities of harm.
- Qualified researchers only: Only scientifically qualified persons should conduct the experiment, and the highest degree of skill and care should be required at every stage.
- Freedom to stop: The subject must be free to end their participation at any point if they feel they have reached a state where continuing seems impossible.
- Researcher’s duty to stop: The researcher must be prepared to terminate the experiment at any stage if they have probable cause to believe continuing will result in injury, disability, or death to the subject.
These principles may sound like common sense today, and in a way, that is the Code’s greatest achievement: it helped make these ideas feel obvious. In 1947, nothing like this existed in a formal international document attached to legal proceedings.
Why the First Principle Towers Over the Rest
If you read the original text, the structural emphasis on voluntary consent is striking. Each of the other nine principles gets a single sentence. The consent principle, by contrast, is followed by two full explanatory paragraphs spelling out exactly what “voluntary consent” means. The person must have the legal capacity to consent. They must be free from “force, fraud, deceit, duress, overreaching, or other ulterior form of constraint or coercion.” And they must have “sufficient knowledge and comprehension of the elements of the subject matter involved as to enable him to make an understanding and enlightened decision.”3PubMed Central. Beyond Nazi War Crimes Experiments: The Voluntary Consent Requirement of the Nuremberg Code at 70
This level of detail was deliberate. The Nazi experiments were not failures of scientific design or risk management alone; they were, at their core, performed on people who had no choice. Concentration camp prisoners could not refuse. The judges clearly felt that if one principle needed to be ironclad and unmistakable, it was this one. The specificity of the consent language also set a high bar that later codes would actually soften. The Nuremberg Code’s consent requirement is absolute: no exceptions for children, for people with cognitive impairments, or for emergency situations where a patient cannot consent. Later frameworks would introduce the concept of surrogate consent for people who cannot consent for themselves, but the Nuremberg Code does not. Some ethicists have pointed out that, taken literally, the Code would prohibit pediatric research entirely, since children cannot give their own informed consent.
The Requirement for Animal Testing
Principle three’s requirement that human experiments be grounded in prior animal studies has had a long afterlife. This principle helped formalize the expectation, carried into national and international laws since 1947, that animal modeling should come before human trials.4PubMed Central. The Nuremberg Code subverts human health and safety by requiring animal modeling The idea is intuitive: test a drug or procedure in animals first, learn what you can about its risks, and only then consider whether it is safe enough to try in people.
This principle has drawn criticism from two opposite directions. Animal rights advocates argue it institutionalized animal suffering. On the other side, some biomedical researchers have pointed out that animal models are often poor predictors of human responses, meaning that mandating animal testing can create a false sense of security while also delaying treatments that might be safe in humans. These debates continue, but the principle’s origin in the Nuremberg Code gave it a moral authority that has made it difficult to challenge in regulatory settings.
The Self-Experimentation Exception
Principle five contains a curious wrinkle. It states that no experiment should be performed where there is reason to believe death or disabling injury will occur, “except, perhaps, in those experiments where the experimental physicians also serve as subjects.” This exception is a nod to a long tradition in medicine where researchers tested dangerous procedures on themselves before asking others to undergo them. It also carried echoes of the yellow fever research of the early twentieth century, where physician Walter Reed’s colleagues deliberately allowed themselves to be bitten by infected mosquitoes.
This provision still sparks debate. During the COVID-19 pandemic, discussions about human challenge studies (where healthy volunteers are deliberately infected to test vaccines) raised the question of whether researcher self-experimentation changes the ethical calculus. As one analysis noted, the Nuremberg Code “posits that high-risk studies might be more acceptable when researchers themselves serve as volunteers,” but this idea remains controversial, partly because clinical and research staff could feel pressure to participate.5The Lancet Infectious Diseases. Ethical considerations of SARS-CoV-2 human challenge studies The line between volunteering and being expected to volunteer can blur in a lab or hospital hierarchy.
Regulations That Came Before
One common assumption is that the Nuremberg Code was humanity’s first attempt to regulate human experimentation. It was not. Germany itself had binding regulations on the books from 1931, known as the Richtlinien, which governed new therapies and human experiments. These rules were in some respects stricter than the Nuremberg Code and were intended to promote morally responsible public health research while still encouraging scientific progress.6PubMed. Reichsrundschreiben 1931: pre-Nuremberg German regulations concerning new therapy and human experimentation The bitter irony, of course, is that these regulations remained in force throughout the entire Nazi era and were simply ignored when it came to concentration camp experiments. The existence of the 1931 rules actually undercut one of the defense arguments at the Doctors’ Trial, which claimed there was no established standard against which the experiments could be judged.
What made the Nuremberg Code different was not that it invented the idea of research ethics but that it connected those ethics to an international legal proceeding. The principles were embedded in a judgment about crimes against humanity, giving them a moral weight that earlier administrative guidelines lacked.
Legal Standing of the Code
The Nuremberg Code occupies an unusual legal position. It was never ratified as a treaty. No country passed a law saying “the Nuremberg Code is now binding in our courts.” Yet its principles were quickly absorbed into international law. A summary version was adopted as an explicit requirement of the Geneva Conventions of 1949, and elements appeared in the International Covenant on Civil and Political Rights in 1966. Legal scholars generally consider it a norm of customary international law, meaning it is widely accepted as binding even without a specific treaty.3PubMed Central. Beyond Nazi War Crimes Experiments: The Voluntary Consent Requirement of the Nuremberg Code at 70
In practice, though, its enforcement record is mixed. No court has ever convicted anyone solely for violating the Nuremberg Code itself. Its influence has been indirect, flowing through the documents and regulations it inspired rather than through direct legal enforcement.
How the Code Shaped Later Ethics Frameworks
The Nuremberg Code was the seed from which modern research ethics grew, but it was not the last word. The World Medical Association adopted the Declaration of Helsinki in 1964, which expanded on the Code’s principles and, critically, allowed for surrogate consent, addressing the Code’s silence on research involving children or adults who cannot consent for themselves. Helsinki has been revised multiple times since then and is the document most directly cited by medical researchers today.
In the United States, the pivotal document is the Belmont Report, published in 1979. It laid out three broad ethical principles (respect for persons, beneficence, and justice) and became the philosophical backbone of federal regulations governing research on human subjects. The process of formulating those regulations involved positioning the principles that contained the Nuremberg Code and Declaration of Helsinki alongside rules specific to each relevant federal institution.7PubMed Central. The creation of the Belmont Report and its effect on ethical principles: a historical study The resulting federal rules, known as the Common Rule, require institutional review boards to approve research involving human subjects before it can proceed.
Internationally, the development of Good Clinical Practice guidelines further codified the Nuremberg Code’s principles into the operational procedures that govern pharmaceutical trials worldwide.8PubMed. Good clinical practice: historical background and key aspects If you have ever been handed a multi-page consent form before joining a clinical trial, you are holding a direct descendant of Principle One.
When the Code Was Ignored
The existence of the Nuremberg Code did not prevent unethical research from continuing in the decades that followed. The most notorious example in the United States is the Tuskegee syphilis study, which began in 1932 (before the Code) but continued until 1972 (well after it). The U.S. Public Health Service enrolled roughly 400 African American men with untreated syphilis and about 200 without syphilis as controls, then tracked them for decades without providing effective treatment even after penicillin became widely available. Among the untreated group, progression to severe, symptomatic syphilis occurred in roughly 20 to 30 percent of participants, compared with 2 to 5 percent in comparable treated groups. The official inquiry concluded that the study was ethically wrong for proceeding without informed consent and for inflicting harms that could have been anticipated, with no offsetting benefit.9PubMed Central. The Rationalization of Unethical Research: Revisionist Accounts of the Tuskegee Syphilis Study and the New Zealand “Unfortunate Experiment”
The Tuskegee study violated virtually every principle in the Code: participants were not properly informed, the risks vastly exceeded any benefit, and the experiment was not terminated when harm became evident. That it continued for twenty-five years after the Code was written illustrates a hard truth. Ethical codes are only as strong as the institutions willing to enforce them. The public outcry after Tuskegee was exposed in 1972 was a major catalyst for the Belmont Report and the modern system of institutional review boards in the United States.
Misuse of the Code in Public Debate
The Nuremberg Code has experienced a strange second life in popular discourse, particularly during the COVID-19 pandemic. Opponents of vaccine mandates, mask requirements, and other public health measures frequently cited the Code as proof that such policies were illegal or equivalent to Nazi experimentation. These claims misunderstand what the Code covers and how it applies.
The Code governs medical experimentation on human subjects. It does not address public health regulations, approved medical treatments, or vaccination programs using licensed vaccines. A government requiring proof of vaccination for school enrollment or certain jobs is exercising public health authority, not conducting an experiment. The distinction matters: an experiment is a procedure performed to generate new knowledge, where the outcome is uncertain by design. Administering a vaccine that has already been tested, approved, and monitored through post-market surveillance is not experimentation in the sense the Nuremberg judges meant.
The comparison also trivializes the original context. The experiments that gave rise to the Code involved people imprisoned in death camps, subjected to procedures designed to maim or kill, with no possibility of refusal and no expectation of personal benefit. Equating that with a vaccination requirement at a pharmacy oversimplifies both the history and the ethics involved.
Gaps and Limitations the Code Did Not Address
For all its importance, the Nuremberg Code left significant territory uncovered. It says nothing about how research data should be stored or shared. It does not address compensation for participants who are harmed. It does not discuss conflicts of interest, such as when the researcher conducting the experiment stands to profit from its results. It has no mechanism for independent oversight, no requirement for an ethics committee or review board to approve a study before it begins. All of these gaps were eventually filled by later documents and regulations, but they are worth noting because people sometimes treat the Code as a comprehensive ethics charter. It is better understood as a starting point: a set of minimum conditions that were so clearly violated by the Nazi experiments that no reasonable person could object to them.
The Code also reflects the legal and social norms of 1947 in ways that now feel dated. Its language uses “he” and “him” exclusively. More substantively, it frames the relationship between researcher and subject in purely individual terms, with no concept of community engagement or the structural power imbalances that can make consent less than fully free even in the absence of overt coercion. A prisoner in a concentration camp is obviously unable to consent. But what about a desperately ill patient with no other treatment options? Or a financially struggling person offered payment to join a risky study? The Code does not wrestle with these shades of gray. Later frameworks tried to, with varying success.