Secret Science is an extensive study of human experimentation undertaken within the chemical- and biological-weapons research programmes of the twentieth century, with a primary focus on the British programme, but also exploring those in the US, Canada and Nazi Germany. Using archival sources, information from the 2004 Maddison Inquest, and interviews with veteran test subjects and former scientists of experimental institutions, Schmidt examines the complex relationships, pressures and interests that make up these programmes (and their volunteers), and specifically focuses on how they contributed and responded to the changing field of medical ethics over the course of the century.

Chapter 2 looks at the genesis of the European chemical-warfare programmes as responses to the gas attacks at Ypres, a situation in which there was “no time to worry about ethics” (p. 28). Schmidt charts the establishment of Porton Down in the First World War, Britain's large-scale non-conventional weapons research and development facility, and the recruitment process set up by Porton after the war to enlist services volunteers as ‘human observers’ (test subjects) for experiments with chemical agents. This raised legal requirements that subjects give informed consent and scientists perform experiments with ‘due care and skill’. Consent features as a key focus in Schmidt's account, unsurprising given his primary interest in the history of medical ethics. Chapter 3 introduces another core question of the book – that is, how ‘secrecy trumps ethics in decision making’ (p. 75) – in an examination of the ways German military scientists dealt (or did not deal) with ethical dilemmas prior to and during the Second World War, including those associated with human experimentation. Schmidt's work becomes most interesting as he begins to unwrap this question in the following chapters. He identifies how secrecy, national security concerns and the emergency state of being ‘at war’ became justifications for the suspension of ethical principles in extensive Allied programmes of human experimentation that began to involve the most toxic chemical agents in the world. Chapter 4 gives a disturbing account of UK, US and Canadian experimentation on servicemen during the Second World War, when ‘breaches of peacetime ethical standards, of safety regulations, and of risk-assessment and informed consent protocols were not the exception but the rule’ (p. 132).

Chapters 5 and 6 chronicle the impact of the Allied discovery of German nerve agents at the close of the Second World War, which provided Porton, for example, not only with its post-war raison d’être but also with the justification for significant expansion. Schmidt explores the way in which the principles of the Nuremberg Code were interpreted within, and assimilated into, military medical research practices and environments. The military medical community felt that the code undermined their moral and scientific authority, and many demanded that the ‘principles be softened to align them with the “capabilities of the average investigator”’ (p. 200). Yet in their highly detached, unsupervised environments, sheltered from transparency while subject to both the privileges and the pressures brought by the Cold War, scientists could conduct increasingly dangerous experiments on humans regardless of the code. As a result, on Wednesday 6 May 1953, twenty-year-old aircraftman Ronald Maddison died after being subjected to the nerve agent Sarin, a case that remains central throughout Schmidt's book.

Chapter 7 examines post-war British and US chemical and biological testing outside laboratories, in many cases involving local populations who had no knowledge that a test was taking place, let alone given informed consent. Most striking is Schmidt's discussion of Porton's trials with Bacillus globigii spores (now considered a pathogen for humans but understood as harmless at the time) on the London Underground in 1963. Chapter 8 documents the rise of the need for the ethical legitimacy of research practices in the late 1950s and the 1960s, which occurred alongside a shift in focus from ‘maximum lethality’ towards ‘maximum incapacitation’ in developing chemical agents. However, Schmidt argues that improved ethical standards at Porton did not occur because of increased respect for international human rights (or the well-being of participants), for medical law or for codified principles, but because of the breakdown of trust and of the relationship between Porton and senior government officials, a breakdown that began with the death of Ronald Maddison. The development of formal safety procedures was necessary for Porton both to maintain political, moral and scientific legitimacy, and to protect the reputations and lives of its own staff, some of whom were resigning after suffering ill effects from tests they had performed on themselves. Schmidt identifies this transition in medical ethics as Porton's attempt to survive and to safeguard the professional status of its scientists. In doing so, these scientists began to employ ethical codes as legitimating tools for their work, using their status as medical professionals to claim authority in setting the boundaries and limits of these codes (and of human experimentation), a process Schmidt details in Chapter 9 with a fascinating account of negotiations behind the Declaration of Helsinki. In the final two chapters, Schmidt deals with how military research institutions attempted to manage and negotiate growing ethical concern and criticism from the public regarding human experimentation. Specifically, the final chapter records the legal battles – including the reopened Maddison inquest – fought in recent years by veteran test subjects seeking both compensation and an apology from Porton for the negative impacts the experiments, performed without their informed consent, had on their lives. Schmidt, having served as an expert witness in the trial, draws out the complexities of how different levels of culpability and ethical violation (in experiments fifty years prior) were established in retrospect, and dissects the politics that construct accounts of medical memory.

Schmidt's account of the role of medical ethics in chemical- and biological-warfare establishments is incredibly complex, involving the research cultures and resources of establishments; individual career interests; the power of scientific expertise; and the professional and political networks linking expert scientists, government agencies and military medicine and science – Porton ‘needed the expertise of civilian scientists as much as civilian scientists needed the expertise of Porton’ (p. 182). At times the book risks feeling disjointed as it navigates back and forth through large amounts of information, but it is nonetheless compelling both as an enlightening account of shocking human experiments that have taken place over the last century and as an important contribution to literature on the history of medical ethics and the culture, networks and politics of military research in general.