Assertions from Osama bin Laden's family that the killing of the Al Qaeda leader was illegal have been dismissed by the White House.

“Are you kidding?” said Vice President Joe Biden when asked Tuesday about the family's calls for international bodies to investigate the legality of the assassination.

In fact, the family is serious.

International law has been "blatantly violated" and the US has set a very different example than "innocent until proven guilty" – a right upon which "western society is built," wrote Omar bin Laden, one of the 9/11 mastermind's 19 children, in a statement provided to the New York Times. He cited the trials for former Iraqi President Saddam Hussein and former Serbian President Slobodan Milošević and asked why his father was not given the same opportunity to defend himself.

IN PICTURES: Osama bin Laden death - reaction

In the statement, the bin Laden family members called on the International Criminal Court, the International Court of Justice, and the United Nations to provide answers, and threatened legal action if their request was ignored. The letter notes that just as Omar publicly criticized his father's use of violence, so too would he and his brothers now "condemn the president of the United States for ordering the execution of unarmed men and women."

The bin Laden family also criticized the US for firing on unarmed people in the compound during the raid and for burying Osama bin Laden at sea instead of notifying the family to conduct a proper burial. The letter called on Pakistan to release all the family members in custody.

White House on defensive

The White House has shrugged off the young bin Laden's grievances.

An unnamed US official told Bloomberg News that because Al Qaeda had declared war on the US, Osama bin Laden was deemed an enemy combatant. The official cited Article 51 of the UN charter, which allows a nation to act in self defense.

His comments echoed US Attorney General Eric Holder, who said in a Senate hearing last week that because bin Laden was considered an enemy commander, targeting him was lawful. Days after 9/11, Congress passed the Authorization for Use of Military Force Act allowing the US president to use "all necessary and appropriate force" against anyone who "planned, authorized, committed, or aided" in the execution of the 9/11 attacks.

The international organization Human Rights First said the White House, and not Omar bin Laden, appeared to be on firm legal footing. "Assuming the existence of an armed conflict against Al Qaeda, Osama bin Laden was targetable unless he was surrendering or so injured as to no longer be apparently capable of engaging in hostilities," it said in a statement.

While Bin Laden was unarmed, according to accounts from US officials, he resisted arrest. Had he "thrown up his hands, surrendered, and didn't appear to be representing any kind of threat," said CIA Director Leon Panetta, then the Navy SEAL team should have captured him.

Amid contradicting accounts of the Navy SEAL raid, however, it is unclear to what extent bin Laden resisted. In the initial account, bin Laden was armed – a claim the US later retracted. Since then, the US has maintained that bin Laden resisted, but did not provide more details.

Legal experts question legality

The legal defense of killing bin Laden rests in part on whether the US was actually at war with Al Qaeda. Claus Kress, director of the Institute for Criminal Law and Criminal Procedure at the University of Cologne, told German news magazine Der Spiegel that the US defense – that bin Laden was an enemy combatant because the US and Al Qaeda are at war – is suspect.

It is "questionable whether the USA can still claim to be engaged in an armed conflict with Al Qaeda," Professor Kress told Der Spiegel.

According to Der Spiegel, the laws of war "permit the targeted killing of non-state combatants, provided they are really combatants who are organized in units with a military-like character, and that they are integrated into those units either as armed fighters or as a leader who issues commands."

The US does have an executive order prohibiting assassinations, although the Council on Foreign Relations explains that this does not apply to military action in an ongoing armed conflict, nor situations of self defense.

But whether bin Laden was still a "military-like" leader and whether Pakistan can be considered within the territorial boundaries of the war with Al Qaeda is up for debate.

"It is in no way clear that bin Laden, at the time of his killing, commanded an organization that was conducting an armed conflict either in or from Pakistan," Kress said.

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