Medical malpratice is strictly related to the methodical adoption of legal proceedings in order to allocate the risk connected to every medical decision (diagnostic as well as therapeutic). The rise of this phenomenon, and it continuos spread has modifying the physician-patient relationshipd in the last decades, which contributes to the consequences on the increasing health system (e.g. defensive medicine). While the heavily struck U.S. medical practitioners insurance market by a recent availability ad affordability crisis has provided us a good example, Italy is at the outset of a quite similar experience. In this paper I have used a comparative approach to deal with the economical and legal features of the common kernel of every health organization on both: the patient-physician relationship (agency model) and the costant inability, partially due to social transformations, of the non-market institution represented by the patient-physician relationship that has addressed the last risk bearer problem as one of the main incentive on a medical decision. Therefore the paper is focused on 1) the legal alternatives to a) induce an efficient level of precaution and b) to reduce the agency model inefficiencies; 2) third institutions' definition and operation (HMOS, ASLS) on (b).