Leading article: More than a legal nicety

If nothing else came out of the Iraq inquiry yesterday, the importance of the legal advice given by the Attorney General, Lord Goldsmith, in the run-up to war was made abundantly clear. There were hints of how central this was at the time, in all the rumours and delays around what sometimes appeared an unseemly scrabbling around for any legal justification. There were indications afterwards in the adamant refusal of the then Prime Minister and Downing Street to release the full text of the Attorney General's ruling. And there were subsequent claims, in the run-up to this inquiry, that the Attorney General was "bullied" into the ruling he was eventually to give.

What yesterday's testimony added was precisely why it was so essential that he rule as he did. Quite simply, the legality of the whole enterprise hung on it, because the advice provided until that point had gone unambiguously the other way. The two senior lawyers at the Foreign Office had concluded that going to war without UN authorisation would be illegal. Both Sir Michael Wood and his deputy, Elizabeth Wilmshurst, had advised, in fact, that invading Iraq without a specific UN resolution would be nothing less than "the crime of aggression".

With senior military commanders concerned that they could put themselves on the wrong side of the law if they sent troops to Iraq in such circumstances, and with the legality of the war a key weapon in the armoury of the growing number of protesters, lack of legal authorisation – if exposed – had the capacity to halt the whole enterprise in its tracks.

Now it is true that many aspects of international law remain contested because there is no way for them to be enforced. It is true, too, that in the UK, which has no written Constitution, the relationship between the elected government and the law is more fluid than it is in many other countries. It was open to the Government to reject the legal advice it received – as, indeed, the then Foreign Secretary, Jack Straw, unusually did here. But when the Prime Minister of the day has built his case for war on the basis that Iraq is in breach of international law, legal authority takes on a new, and overriding, significance. Lord Goldsmith gives his version today.