The nature of Ultima Ratio as a principle, its relationship to other principles in the criminal law is the first subject of this paper. After discarding approaches that deny any role to the ultima ratio principle like the criminal law of the enemy, the major readings of the justification of the ius puniendi – deontological and utilitarian – are related to the idea of a restrained resort to criminalisation and penal sanction. The role of the main protagonists in relation to punishment is next considered: transgressor, community and victim. The issues of impunity and overpunity are also considered in this part. The second part of the paper analyses the possible effects of ultima ratio, a general politico-moral principle mainly add...