The UK (as indeed the US) gave as its formal legal ground for the invasion of Iraq reliance upon interpretations of Security Council resolutions. In other words, there was no open admission by official legal advisers that the British invasion of Iraq created a new precedent for the development of international law, in particular a doctrine of pre-emptive attack. However, an understanding of state practice as a source of customary international law requires that one challenge the view that a

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... e's contribution to practice must be taken to be its stated legal position. Instead, one has to engage in an in-depth study of the motivations of state officials that move the institutions of the state. These need to be pieced together from official declarations and also from the work of known government advisers who are systematically developing policy with legal implications. Furthermore, one needs to consider the practice of a state as embedded in institutional continuities, including especially institutional planning for the future. This can be gleaned from a variety of official documents, such as White Papers, which set out the purposes for which institutions of the state, especially the armed forces, are being shaped. On this basis it is clear that the UK has committed itself to set a precedent for pre-emptive attack through its invasion of Iraq. That is clear from the studies considered in this essay. There is a serious need to place British, and of course American, state practice, as represented by the invasion of Iraq, in the wider context of the development of international