'Illegality' as mere attitude
It is not at all uncommon these days to come across the opinion that the Iraq war was illegal. This opinion is especially doing the rounds now, as the fifth anniversary of the beginning of the war approaches. Baroness Tonge gave expression to it over the weekend; Jonathan Steele thinks the same as she does; so do Bianca Jagger and Michael D. Higgins, foreign affairs spokesman of the Irish Labour Party, and many others besides.
Coming from such figures, the statement that the Iraq war was illegal has approximately the same status as the statement that they were opposed to that war; only, putting it in the way they do makes their opinion sound as if it had greater force. I'm aware in saying this that there are people with some expertise in international law who also say the war was illegal. Nonetheless, it is untrue to say this as if it were authoritatively established. Here are some relevant considerations.
As well as the opinion of legal scholars that the Iraq war was illegal there is also legal opinion to the contrary, and the argument between the two views has not yet been put to the test.
If the illegality of the war is held to follow from the fact that those who prosecuted it did so without the authorization of the UN Security Council, then the Kosovo intervention in 1999 was also illegal. Naturally, that by itself doesn't show that the Iraq war was legal, but it poses a problem for all those - and I would estimate their number to be large - who think it was illegal but seemingly have no desire to see Bill Clinton put on trial. More importantly, the intervention in Kosovo stands as a precedent in any argument about the legality of the Iraq war if this should come to a decisive adjudication.
Most decisively to my mind, the UN Security Council, the very body whose putative authority in this domain was bypassed in 2003, has by its own resolutions put the stamp of legitimacy on the transitional arrangements in Iraq that came out of the US-led invasion. It's at least possible that this fact would carry weight in any final determination of the legality of the war. It is logically possible, of course, to hold that an act bringing about a state affairs judged to be legal is itself illegal. But it is easier to arrive at such a conclusion where you already have an unambiguous determination of the illegality of the act. Where the status of the act is in doubt, and the putatively legitimating body (here the UN Security Council) more or less immediately validates the arrangements put in place by it, that must strengthen the case made by legal advocates for the legality of the act, particularly in a system where custom and precedent are important.
