Richard, you seem very certain of the law on this.
Are you better informed than all these?

Was the killing of Bin Laden legal?

The use of deadly force against Bin Laden, who was said to be unarmed, is unlikely to be challenged in an American court, but the US has already sought to defend its position on legal grounds.

US Attorney General Eric Holder said the acts taken were "lawful, legitimate and appropriate in every way".

US legal experts point to the fact that the US had declared itself to be in armed conflict with al-Qaeda.

Kenneth Anderson, a fellow in national security and law at the Hoover Institution, told Reuters: "It's lawful for the United States to be going after Bin Laden if for no other reason than he launched an attack against the US."

Other legal experts questioned whether this would stand up under international law.

Targeted killings under US law remains a disputed area.

US executive order 12333, signed by President Ronald Reagan, says: "No person employed by or acting on behalf of the United States government shall engage in, or conspire to engage in, assassination."

However, the term assassination has never been fully defined and some US legal advisers have sought to argue it does not apply in conflict situations.

State department legal adviser Harold Koh, quoted by Mr Anderson, said in March: "Under domestic law, the use of lawful weapons systems - consistent with the applicable laws of war - for precision targeting of specific high-level belligerent leaders when acting in self-defence or during an armed conflict is not unlawful, and hence does not constitute 'assassination'."

Profs William C Banks and Peter Raven-Hansen, writing in the University of Richmond Law Review, also argue it does not apply to figures such as Bin Laden, nor when the US is "in hostilities such as the Gulf War or war on those responsible for the 11 September attacks".

"The targeted killing of terrorists is therefore not unlawful," they conclude.

Mindful of its need to stress the military nature of the killing and the need to abide by conventions, the US has also said that Bin Laden presented a clear danger to its troops.

CIA director Leon Panetta said: "Obviously, under the rules of engagement, if he had in fact thrown up his hands, surrendered and didn't appear to be representing any kind of threat, then they were to capture him. But they had full authority to kill him."

Another US defence official said: "There were certainly capture contingencies, as there must be."

British law professor Philippe Sands QC, of University College London, says the US can certainly argue that it was entitled to take action to protect its citizens against a deadly enemy.

"Even if the use of deadly force was unlawful, international law recognises that there are exceptional circumstances where necessity precludes wrongfulness, and this will be said to be one of those case," Mr Sands told the BBC.

But Mr Sands says that what Pakistan knew and authorised, and what happened when the commandos confronted Bin Laden, will need to be known before the legal situation of the raid becomes clear.

UN High Commissioner for Human Rights Navi Pillay has called for more information and stressed international law must be respected - but accepted that taking Bin Laden alive was always likely to be difficult.