[The epidemiologist in the courtroom: various arguments to start a discussion]

This paper focusses on some topics peculiar to the presence of the epidemiologist in the courtroom and suggests an initial inventory of questions that might be addressed. Epidemiology and law have peculiarities that must be recognized but a specific collaboration between these expertises is necessary. First of all, it is important to admit that scientific discussion is different from courtroom discussion: some simple examples give an idea of the different ways in which the discussion may proceed in each of the contexts and of the difficulties in using traditional epidemiologic tools. Secondly, the concept of general causality (whether an agent can cause a disease) and specific causality (whether an agent did cause a plaintiff's disease) are briefly reviewed, and the role of epidemiology in addressing both question is discussed. The last point regards the use of epidemiologic methodology in the courtroom context, with particular reference to errors, study design, and literature evaluation: a minimum set of criteria for quality assessment is requested.