Zacarias Moussaoui, the “twentieth hijacker” who, prosecutors argued, would have participated in the September 11 hijackings but for the fact that he had been nabbed by authorities before his co-conspirators perpetrated the attack, moved one step closer to the gallows yesterday. If he dies for his crime, it will be, in effect, a rare case of capital misprision, namely, the crime of failing to report a crime. By failing to alert law enforcement to the impending attack in which he was to have participated, Moussaoui effectively abetted the crime despite his inability to participate in person. A federal jury in Virginia has found that his omission led directly to the loss of at least one life in the terrorist attack. The verdict will send a clear message – in the war on terror, silence can be as deadly as a box cutter, and will be taken as seriously.

The jury’s verdict is not the last word on Moussaoui’s sentence; now that the jury has found him eligible for the death penalty, it must hear additional testimony before deciding whether to mete out that penalty or whether instead to allow him to live out the rest of his life behind bars. Execution appears ever more likely. Even after weeks of relatively esoteric legal testimony, the jury was willing to entertain the possibility of a death sentence. Now it will hear from victims’ families, unlikely to sway toward leniency.

Moussaoui was not an otherwise innocent bystander who saw a crime occur but couldn’t be bothered to call the police. He wasn’t a conspirator who got cold feet but was afraid to turn in his erstwhile comrades before they could commit a felony. Rather, he was with the 19 “successful” hijackers in spirit if not in person – his silence was calculated to allow them to carry out their terrorist act unhindered.

Yet even before a final decision has been reached on Moussaoui’s fate, legal scholars were already voicing concern about the precedent that would be set by handing down a death sentence for misprision, that is, for failing to act. It is a question that’s sure to preoccupy America’s legal system for years to come as Moussaoui’s expected appeals wend their way through the courts. And it should be the subject of vigorous debate. Powerlineblog.com started things off with a post on the point within minutes of the jury’s verdict being reported. If the idea of capital misprision is ever to prosper, it’s hard to imagine a more compelling case than Moussaoui’s failure to act to abort the plot that achieved its object on 9/11.