Big tobacco focuses on the facts to hide the truth: an algorithmic exploration of courtroom tropes and taboos.

Objective: To use methods from computational linguistics to identify differences in the rhetorical strategies deployed by defence versus plaintiffs' lawyers in cigarette litigation.

Methods: From 318 closing arguments in 159 Engle progeny trials (2008-2016) archived in the Truth Tobacco Industry Documents, we calculated frequency scores and Mann-Whitney Rho scores of plaintiffs versus defence corpora to discover 'tropes' (terms used disproportionately by one side) and 'taboos' (terms scrupulously avoided by one side or the other).

Results: Defence attorneys seek to place the smoker on trial, using his or her friends and family members to demonstrate that he or she must have been fully aware of the harms caused by smoking. We show that 'free choice,' 'common knowledge' and 'personal responsibility' remain key strategies in cigarette litigation, but algorithmic analysis allows us to understand how such strategies can be deployed without actually using these expressions. Industry attorneys rarely mention personal responsibility, for example, but invoke that concept indirectly, by talking about 'decisions' made by the individual smoker and 'risks' they assumed.

Conclusions: Quantitative analysis can reveal heretofore hidden patterns in courtroom rhetoric, including the weaponisation of pronouns and the systematic avoidance of certain terms, such as 'profits' or 'customer.' While cigarette makers use words that focus on the individual smoker, attorneys for the plaintiffs refocus agency onto the industry. We show how even seemingly trivial parts of speech-like pronouns-along with references to family members or words like 'truth' and 'facts' have been weaponised for use in litigation.