A friendly critical analysis of Kass's ethics framework for public health.

Kass's framework has played a seminal role in stimulating reflections on the ethics analyses of public health programs. This framework stipulates that public health programs should not be implemented if there are not at least some existing data to demonstrate the validity of their "assumptions". The purpose of this commentary is to provide a constructive critical analysis of this framework. We argue that it is difficult to adopt Kass's framework in the public health field, in part because of the labile definition of what constitutes "data" or "evidence". Moreover, we argue that public health actors have the responsibility to base their interventions on the best available evidence, but that when data do not exist they may still be required to intervene with prudence to protect the health of the population. In such cases, policy-makers should first implement pilot interventions coupled with rigorous monitoring mechanisms, independent evaluations and ongoing dialogue with stakeholders so that public health measures can be modified or adapted quickly to avoid unintended harm to the population. Populations can also participate in the assessment of the interventions' risks and acceptability to avoid paternalistic approaches. We conclude that more flexible frameworks may be more useful in the field of public health.