In an article published a few years ago, my friend Jakob Holtermann compared the International Criminal Court (ICC) to a slice of Swiss cheese. The metaphor is meant to indicate that the ICC operates as a filter that deters some of the criminals left undeterred by national criminal law systems. This is true. But the metaphor also suggests that the ICC would only deter extra criminals and would not damage the deterrence achieved by preceding filters, which is false. This article explains why.