By Paul Reynolds
World affairs correspondent, BBC News website
The evidence from two former Foreign Office lawyers has thrown large pebbles into the waters of the Iraq inquiry.
Elizabeth Wilmshurst had some acerbic words for Jack Straw
The first was the revelation from the then senior legal adviser Sir Michael Wood that he took the view that an invasion of Iraq would be illegal without a specific UN Security Council resolution authorising it.
Up until now it had been thought that his deputy, Elizabeth Wilmshurst, who resigned over the issue just before the invasion, was a lone voice.
The second ripple was caused by Ms Wilmshurst herself.
She came across as a rather quiet, though determined, witness but in some very sharp language she criticised not only the decision to go to war but the way in which the opinion of Attorney General Lord Goldsmith had been left to the last minute.
It had been "a "lamentable" process, she stated, and said that in future the attorney's view should be sought before troops were deployed in substantial numbers.
All this emphasised how the British role in the invasion of Iraq was hanging by the slender legal thread held by Lord Goldsmith.
It was not until 17 March 2003, three days before the fighting started, that he delivered his opinion to Parliament. This was that Security Council resolution 1441 had given Saddam Hussein a final warning and that no further resolution was legally necessary.
What also emerged from the inquiry was the role of international law in the debate within the British government in the run-up to the invasion.
The picture painted has been a murky one, not least because everything was done in secret.
There was strong legal advice against a war and everything hung on the attorney general, whose opinion is by convention taken as the last word on the legality of any British government action.
He was under considerable pressure and had initially taken the view that there were no grounds for an invasion.
There was no question, he had said, of self defence or humanitarian intervention and no authorising Security Council resolution.
It was not until the last minute that he came to the view that, after all, the original ceasefire resolution 687 following the Gulf War in 1991 was "revived" by Saddam's failure to comply with later resolutions, notably 1441.
If Lord Goldsmith had opposed the war on legal grounds, Britain could not have taken part.
The views of Foreign Office lawyers were not accorded such status.
The clash between them and their political leader, Foreign Secretary Jack Straw, is highly instructive in revealing the relationship between politicians and their legal advisers.
As Margaret Thatcher said in another context: "Advisers advise. Ministers decide."
In one letter to Lord Goldsmith, Mr Straw, a lawyer himself, was dismissive of his advisers: "I have been very struck by a paradox in the culture of government lawyers, which is that the less certain the law is, the more certain in their views they become."
Ms Wilmshurst, in her evidence, had an answer to this. It was that the less certain international law was (and there was no court which could rule in this case), it was all the more important that government behaved with caution.
She also took a swipe at Mr Straw himself.
Asked by the inquiry chairman Sir John Chilcot whether the fact that Mr Straw was a "qualified lawyer" was important, she replied: "He's not an international lawyer."