This chapter is the third in a trilogy on the role of lawyers in giving prior advice on the legality of wars being contemplated by sovereign states – stimulated by the Kosovo and Iraq wars in 1999 and 2003. It considers the ethical issues confronting Lord Goldsmith in advising the government of which he was a part on the legality of the latter. His long advice provided on 7 March 2003,1 was by far the best advice by a senior government lawyer that has so far come to light, canvassing both sides, pointing out that only the Americans took the view that the invasion would be legal and addressing some of the ways in which the matter might come to court.2 What should a lawyer in his position do – as a lawyer, as a member of the government, as the first law officer of the crown (and to what extent do these multiple roles either produce different answers or modify the answers provided in each)? This chapter argues that the answers to these questions can be most helpfully framed by the arguments about how lawyers should deal with ‘delinquent clients’ who tell their lawyers, in advance, that they intend to engage in activity that the lawyer considers to be a crime, fraud or tort – especially those acts which are likely to lead to serious harm to another. Examples discussed in the case law and literature range from where clients plan to commit fraud by submitting a claim to which they were not entitled, taking a child out of the jurisdiction following a custody visit, committing perjury, planning to sell a stolen car to pay for a lawyer’s fee, to murdering a spouse’s boyfriend.3 In this discussion, I will refer to other wars and other countries and build on other work about the legality under domestic and international law.4 I will also canvas the question of how we might improve our procedures for going to war. But I should begin with the impetus for the first of these three essays.