Professor Burnham specializes in the history of medicine and American social history. His particular interest is the history of psychiatry. His recent books include How Superstition Won and Science Lost: Paths into American Culture: Psychology, Medicine, and Morals (1988), Bad Habits: Drinking, Smoking, Taking Drugs, Gambling, Sexual Misbehaviour, and Swearing in American History (1993), and What Is Medical History? (2005). Burnham is presently studying the impact of Freud on the Western world, and also the deinstitutionalization of mental patients in the 1950s.
Professor Burnham has taught at Stanford University. He has served as President of the American Association for the History of Medicine and has held many other offices in scholarly organizations both in the United States and abroad, and he is a Fellow of the American Association for the Advancement of Science.
Burnham has been a vocal supporter of those historians who are willing to testify for the tobacco industry. The Lancet of 2004 debated the role of historians in tobacco trials. Historian and expert witness Robert Proctor had written an article that condemned historians who testified for the tobacco companies. Burnham wrote a short reply to defend the historians who were working with tobacco companies. In 2010, Burnham also wrote a reaction to historian Jon Wiener’s article in the Nation on the same subject. Burnham defended historians who served as expert witnesses for the tobacco industry. Claiming that “everyone has a financial interest.” Burnham has also served in a number of other court cases as a consultant for asbestos, lead, and soda companies. Proctor noted in his article from 2006 on historians as expert witnesses in tobacco-related litigation that Burnham functioned as a recruiter of new expert historians for the legal firms defending the tobacco industry.
Burnham is one of the few historians who has served as an expert witness for the tobacco industry who had done research on the history of tobacco previous to his litigation work. Burnham is also the only expert working for the defence who is willing to discuss his work as an expert witness in tobacco litigation at length in public or with his peers.
 For the debate in The Lancet see: Proctor, Robert. 2004. Should Medical Historians Be Working for the Tobacco Industry? The Lancet 363, 1174-1175. & Proctor, Robert. 2004. Medical Historians and the Tobacco Industry, Author’s Reply. The Lancet 364, 838. & Burnham, John. 2004. Medical Historians and the Tobacco Industry. The Lancet 364, 838.
 For the debate in The Nation see: Wiener, Jon. 2010. Big Tobacco and the Historians. The Nation, February 15. http://www.thenation.com/article/big-tobacco-and-historians. Accessed 31 Oct 2014. & Wiener, Jon. 2010. Re ‘Big Tobacco and the Historians’, Wiener Replies. The Nation, March 9. http://www.thenation.com/article/re-big-tobacco-and-historians. Accessed Oct 31 2014. & Wiener, Jon. 2010. Smoking Gun … Wiener Replies. The Nation, April 19. http://www.thenation.com/article/letters-337. Accessed 31 Oct 2014. & Burnham, John. 2010. In Defense of Historians as expert Witnesses: A Rebuttal to Jon Wiener. George Mason University’s History News Network, April 1. http://hnn.us/articles/124924.html. Accessed 31 Oct 2014.
 Cohen, Patricia. 2003. History for Hire In Industry Lawsuits. The New York Times, June 14. http://www.nytimes.com/2003/06/14/arts/history-for-hire-in-industry-lawsuits.html?pagewanted=all&src=pm. Accessed 31 Oct 2014.
 Cohen, as n. 3.
 Proctor, Robert. 2006. ‘Everyone Knew But No One Had Proof’: Tobacco Industry Use of Medical History Expertise in US courts, 1990-2002. Tobacco Control 15, 121.