C. What if your country is not a state party to the Rome Statute?
If the court does not have territorial or personal jurisdiction over a crime, there are two other circumstances in which the ICC can exercise limited jurisdiction on a case by case basis. They are:
• The government of country that is not a State Party may make a declaration under Article 12(3) that it is going to accept the Court's jurisdiction over it's territory and its nationals in relation to a particular incident. However, this requires those in power in a given country to voluntarily give the court jurisdiction in a given case. As the Crimes covered by the Rome Statute tend to be crimes of the powerful, this may be very difficult to bring about.
• The Security Council of the United Nations may deem a particular situation to be a threat to international peace and security under Chapter VII of the UN Charter. If it does this, it may decide to refer the situation to the ICC so that it can prosecute individuals involved. (Note that this requires consensus among the five permanent members of the Security Council (China, USA, Russia, United Kingdom and France) and so may be very difficult to bring about.)
The best way to ensure that serious breaches of international criminal law in a country do not go unpunished is to lobby the government to ratify the Rome Statute. If you are working on human rights in such a country, the Coalition for the International Criminal Court website has useful materials for those lobbying governments to ratify the Rome Statute.