Meanings & motives. Experts debating tobacco addiction.

Over the last 50 years, tobacco has been excluded from and then included in the category of addictive substances. We investigated influences on these opposing definitions and their application in expert witness testimony in litigation in the 1990s and 2000s. A scientist with ties to the tobacco industry influenced the selection of a definition of addiction that led to the classification of tobacco as a "habituation" in the 1964 Surgeon General's Advisory Committee report. Tobacco was later defined as addictive in the 1988 surgeon general's report. Expert witnesses for tobacco companies used the 1964 report's definition until Philip Morris Tobacco Company publicly changed its position in 1997 to agree that nicotine was addictive. Expert witnesses for plaintiffs suing the tobacco industry used the 1988 report's definition, arguing that new definitions were superior because of scientific advance. Both sides viewed addiction as an objective entity that could be defined more or less accurately.