Some time after sunset on October 14, 2011, a group of teenagers were eating together at an open-air restaurant. Without warning, there was a devastating explosion - so devastating that when residents rushed to the scene, they found nothing left of the six teenage boys who had been sitting there. They had been blown to pieces.

That incident lasted mere minutes but an explanation of what happened that night and why still has not been unearthed and the repercussions of that explanation, if and when it comes, will have far reaching consequences for international law.

Here is what is known: one of those teenage boys was a 16-year old American citizen called Abdulrahman. He had been raised in the United States but had moved to Yemen around 10 years before his death. His father was Anwar Al Awlaki, a firebrand preacher that the US had put on a "kill list" and had assassinated with a drone strike two weeks before. Al Awlaki holds the notorious distinction of being the first US citizen "targeted" by the US government - the first time that the US has said in advance that it would seek to kill one of its own citizens without telling a court why.

Abdulrahman had not seen his father for years. He had left his family home in Yemen's capital, Sanaa, in September 2011 to try to find him, but his father was killed before they met.

Now his grandfather, Nasser Al Awlaki, Al Awlaki's father, and a former government minister in Yemen, is challenging the US in court to try to find out why he was killed. Writing in The New York Times last week, he said it was not until this past May that the US government admitted it was responsible for the death of the 16-year old, although all the attorney general would say was that the boy was not "specifically targeted".

The case is exposing not merely the extensive secrecy that surrounds the Obama administration's policy of "targeted killings" but also how reluctant the government is to accept any oversight at all. A lawyer for the Obama administration, seeking to have the case thrown out of the Washington court, argued that, in essence, the government had the right to kill US citizens it designated as "dangerous" without any court even reviewing the decision. The judge hearing the lawsuit was shocked: "No, no, no," she said. "The executive is not an effective check on the executive."

Yet, such secrecy and the lack of any oversight is typical of what the US under Barack Obama appears to believe is its right. This is what the American journalist Tom Junod, who has written extensively about the US policy of killing those it deems enemies, exposes when he wrote that the Obama government "speaks as though nothing could be harder than killing individuals and behaves as though nothing could be easier - and carries out what amounts to executions on a mass scale".

Why does this matter? Surely what happened to a couple of US citizens in a country far from home is only of interest to America and those who follow America's policy?

There is, however, a wider point at stake. The Obama administration has arrogated to itself the power of life and death, even over its own citizens. What hope, then, for those who are not? In an interconnected world, it seems anachronistic that citizenship still provides some meagre defence against the excesses of powerful governments. There were five other boys blown apart that day in October, but the only one we are talking about is the one who held US citizenship.

And yet, what the case of Abdulrahman Al Awlaki shows is that Mr Obama has swept away even that flimsy shield. Now, regardless of your passport, regardless of who or where you are, regardless of any evidence against you, the US believes it has the right to kill you and not tell anyone why. That's why the case matters. Whatever crimes Anwar Al Awlaki was accused of and killed for, they do not condemn the son.

It doesn't matter that Abdulrahman, in photographs released by the American Civil Liberties Union, looks like a typical teenage kid, a pleasantly awkward boy that his grandfather described as having "a mop of curly hair and a wide, goofy smile". It doesn't matter that, again as described by his grandfather, he liked The Simpsons and Snoop Dogg. It doesn't especially matter what his views, his hobbies or his clothes were like.

What matters is that he was killed by his own government, a government set up explicitly to protect him. What matters is that, as far as his family knows, and as far as his government will say, he was killed for no reason and without warning.

What matters is that if this is how the US is prepared to act, killing its own citizens without any explanation, without any oversight from the courts, without due process of law or recognition of mistakes, how then will it explain, justify or be held accountable for the hundreds of foreign citizens who have also met their deaths from drone strikes?

falyafai@thenational.ae

On Twitter: @FaisalAlYafai