The threatened war against Iraq will be a breach of the United Nations Charter and hence of international law unless it is authorised by a new and unambiguous resolution of the security council. The Charter is clear. No such war is permitted unless it is in self-defence or authorised by the security council.
Self-defence has no application here. Neither the United States nor the UK, nor any of their allies, is under attack or any threat of immediate attack by Iraq.
Nor is there any authority from the security council. Resolution 1441 does not constitute any such authority as the reference to "serious consequences" is not sufficiently precise to justify war. Whatever the US may have wanted, the resolution was deliberately vague because the council had not agreed on the use of force. A new resolution would therefore be required. It would have to be in unambiguous terms authorising the use of force.
In the absence of such a resolution, the attack would, be unlawful. On this point I agree completely with the terms of the letter from 16 eminent international lawyers to 10 Downing Street published in last Friday's Guardian.
What would be the consequences of such illegality? Most obvious would be the human, economic and environmental costs, including any further violence that a war against Iraq might trigger. An illustration of how unpredictable and incalculable such costs might be is furnished by a recollection of the events of 1914. When the Hapsburg empire attacked the Serbs, the campaign was expected to be short because of the immense military superiority of Austria/Hungary over the Kingdom of Serbia. Four years later, the Hapsburg empire, together with those of Germany and Russia, lay in ruins. A residue of bitterness and hatred was left that bred an even worse war 20 years later in which there were more than 50 million fatalities. Who can say with certainty where today's threatened war might lead?
A second consequence would be of immense world significance, for it would mean the end of the United Nations and with it the final collapse of the efforts of the past century to create effective international institutions that would replace perpetual war with perpetual peace.
If attempts to create such international institutions were abandoned, the clock would be turned back to a time when nations had to depend for their security on the uncertain and shifting patterns of alliances and their own military defences. This would inevitably lead to more being spent on swords and less on ploughshares.