Although the Genocide Convention's title speaks of both prevention and punishment of the crime of genocide, the essence of its provisions is directed to the second limb of that tandem. The concept of prevention is repeated in article I: ‘The Contracting Parties confirm that genocide, whether committed in time of peace or in time of war, is a crime under international law which they undertake to prevent and punish.’ Of course, punishment and prevention are intimately related. Criminal law's deterrent function supports the claim that prompt and appropriate punishment prevents future offences. Moreover, some of the ‘other acts’ of genocide imply a preventive dimension. Prosecution of conspiracy, attempts and above all of direct and public incitement are all aimed at future violations. But the drafters of the Convention resisted going further upstream, rejecting efforts to criminalize ‘preparatory acts’ such as hate speech and racist organizations.

Article I of the Genocide Convention is not merely ‘hortatory or purposive’, insisted the International Court of Justice in its February 2007 ruling on the Bosnian application against Serbia. The undertaking to prevent and punish genocide is unqualified, said the Court. ‘It is not to be read merely as an introduction to later express references to legislation, prosecution and extradition … Article I, in particular its undertaking to prevent, creates obligations distinct from those which appear in the subsequent Articles. That conclusion is also supported by the purely humanitarian and civilizing purpose of the Convention.