Former Gen. Abdulwaheed Shannan Al Rabbat also sought to prosecute Blair's Foreign Secretary Jack Straw and Attorney General Peter Goldsmith because of their involvement in the decision.
The case centered on the concept that a "crime of aggression" would be recognized under English law, as it is under international law. Al Rabbat's lawyers argued that this would have made it possible for the British leaders to be held personally accountable and subject to criminal trials and even prison if convicted for their actions.
However, an inquiry into the Iraq war, led by John Chilcot, concluded that "the invasion was not prompted by the aggression of another country."
The inquiry's conclusion prompted Al Rabat's lawyers to question earlier court decisions and to ask the Supreme Court to review the matter. But the judges rejected that bid, saying it was "for Parliament and Parliament alone" to decide whether "to make such conduct criminal under domestic law."
Khan called on Parliament to enact a law making accountability clear in the future.