The EU has given political, financial and technical support to the court,[1] which is also based in its territory (The Hague, the Netherlands).
[5] The Cotonou Agreement which the EU has with the African, Caribbean and Pacific Group of States includes a binding article signalling support of those states for the ICC and that they should "take steps towards ratifying and implementing the Rome Statute and related instruments".
[6] All its member states have signed and ratified the Rome Statute (which established the court, having come into force in 2002) and hence, due to the lack of other major powers being members, the EU is now the largest financial contributor to the court[1] (before the accession of Japan in 2007, this was 75.6%.
In ways it has operated as a public relations branch of the ICC and encouraged states around the world to adopt the Rome Statute (including putting it in trade agreements, as mentioned above).
Due to the difficulty of the court's work, and opposition from major powers such as the US, this support has been indispensable and, likewise, the EU has been using the ICC as a tool to make its presence felt.