No authority of his own, merely relaying the promises he had been made by those who did - He had been promised that the invasion would hinge on the success/failure of the weapons inspections and sadly he presumed he had grounds and authority to believe it. Incidentally he was not merely a 'government scientist' - he was the head of the United Nations weapons inspection team and had a vast experience in the subject and there was pretty much no-one more senior or better informed than he (who was dealing with the Iraqis, at least). So while Bush and his pals were haranging for war it was down to Kelly and his team as the only people who could resolve the matter peacefully - but of course that was never the plan and when he realised it he tried to blow the whistle through Gilligan.
