A few years ago, when my then-research assistant Zaahira Wyne and I were trying to analyze what sort of people really made up the Guantanamo population---research that eventually went into both Chapter 3 of Law and the Long War and this paper---we developed an intellectual strategy we called the "Duck Test." Zaahira and my problem was that a lot of detainees had done things that were consistent with, but not definitively probative of, membership in enemy groups. They admitted, for example, staying in an Al Qaeda guest house or taking training or being recruited to travel to Afghanistan for jihad-like activity---but they denied actually fighting or joining up. How should one categorize such people?
The Duck Test worked like this: For our analytical purposes, we decided that merely having webbed feet did not make one a duck, nor did waddling, quacking, or any other individual duck-like activity. But as the saying goes, if something walks like a duck, quacks like a duck, and waddles like a duck, it's probably a duck. So in combination, two or more duck-like qualities could be probative of duckdom. In our categorization of detainees, we referred to the Duck Test frequently, and it guided a good many of our categorization judgments.
The courts have, in the years since, struggled with the same problem that troubled Zaahira and me. Many of the habeas petitioners that have come before them have denied being "part of" enemy forces, but admitted facts that a reasonable judge would consider individually as at least somewhat probative of significant affiliation---and in combination paint a very duck-like picture. The lower court judges tended to disaggregate the duck-like qualities and deal with them individually, looking for specific evidence of a detainee's being part of the command structure of Al Qaeda or the Taliban and often not finding it amidst the duck-like qualities. The D.C. Circuit rejected this approach, however, adopting a more holistic and impressionistic approach to evaluating the data it had in each case. To put it simply, the court was looking for ducks--and this week, in the Hussain case, it formally adopted---to Zaahira and my surprise and amusement---the duck test. Writes Judge Thomas Griffith for the majority:
Evidence that Hussain carried an assault rifle given him by Taliban forces while living among Taliban forces near a battle line fought over by Taliban forces brings to mind the common sense view in the infamous duck test. See, e.g., Dole v. Williams Enterprises, Inc., 876 F.2d 186, 188 n.2 (D.C. Cir. 1989) (adopting the “now-infamous ‘duck-test,’ dressed up in appropriate judicial garb: ‘WHEREAS it looks like a duck, and WHEREAS it walks like a duck, and WHEREAS it quacks like a duck, WE THEREFORE HOLD that it is a duck.’”).
In his concurrence in the judgment---which is really a dissent in all material respects---Judge Harry Edwards takes issue with the duck test:
The majority invokes the “walks like a duck” test to conclude that the evidence “at least invites---and may very well compel---the conclusion that [Hussain] was loyal to [enemy] forces.” This is not a proper application of the preponderance of the evidence test with respect to the matter in dispute. And it is quite invidious because, arguably, any young, Muslim man traveling or temporarily residing in areas in which terrorists are known to operate would pass the “duck test.” That is exactly why the court should faithfully apply the proper evidentiary standard.
But having personally gone through a protracted effort to figure out what patterns of behavior do and do not suggest membership in an AUMF-covered group with respect to this population, I suspect that some version of the duck test is inevitable if the courts do not want to free a whole lot of people whom the totality of the evidence suggests are probably "part of" Al Qaeda. This was the bridge the D.C. Circuit crossed in Al Adahi, where it wrote:
Those who do not take into account conditional probability are prone to making mistakes in judging evidence. They may think that if a particular fact does not itself prove the ultimate proposition (e.g., whether the detainee was part of al-Qaida), the fact may be tossed aside and the next fact may be evaluated as if the first did not exist. Prandy-Binett, 5 F.3d at 559-60. This is precisely how the district court proceeded in this case: Al-Adahi's ties to bin Laden "cannot prove" he was part of Al-Qaida and this evidence therefore "must not distract the Court." Mem. Op. at 18. The fact that Al-Adahi stayed in an al-Qaida guesthouse "is not in itself sufficient to justify detention." Id. at 20. Al-Adahi's attendance at an al-Qaida training camp "is not sufficient to carry the Government's burden of showing that he was a part" of al-Qaida. Id. at 25. And so on. The government is right: the district court wrongly "required each piece of the government's evidence to bear weight without regard to all (or indeed any) other evidence in the case. This was a fundamental mistake that infected the court's entire analysis."
The duck test is really just a colloquial way of expressing the same idea.
And no, Zaahira and I never wrote about the Duck Test. The D.C. Circuit has come up with the analogy---apparently already in its own case law---all on its own.