Immunity of States, diplomatic immunity and immunity of other State officials have always been traditional doctrines of customary international law, which have been, thanks to the work of the International Law Commission (ILC), partly codified in international conventions. Currently, work is underway on the codification of immunity of State officials from foreign criminal jurisdiction, which is a very important and sensitive area.
New trends have been introduced by the recent development of international criminal law, excluding immunity from the prosecution before international criminal tribunals. Immunities are still important in situations where the principle of sovereign equality of States must be applied, i.e. before national courts.
The success of the codification will depend on how well functional immunity will be defined as a principle, and on the definition of relevant crimes under international law in respect of which immunity does not apply.