What is the test for establishing quantity attributable to a defendant knowingly participating in a drug distribution conspiracy?

The drug quantity attributable to a defendant knowingly participating in a drug distribution conspiracy includes (1) transactions in which he participated directly, (2) transactions in which he did not personally participate, but where he knew of the transactions or they were reasonably foreseeable to him, and (3) quantities he agreed to distribute or possess with intent to distribute "regardless of whether he ultimately committed the substantive act." United States v. Jackson , 335 F.3d 170, 181 (2d Cir. 2003).⁶

To prove the quantity by one of these means beyond a reasonable doubt, the government must introduce specific evidence of drug quantities, or evidence from which quantity can, through inference, be logically approximated or extrapolated. See United States v. Archer , 671 F.3d 149, 163 (2d Cir. 2011) (requiring "specific evidence" of quantity to sustain quantity-based enhancement). In the absence of such evidence, a jury's finding as to drug quantity is nothing but "surmise and conjecture." United States v. Shonubi , 998 F.2d 84, 90 (2d Cir. 1993). Compare United States v. Shonubi ("Shonubi II") , 103 F.3d 1085, 1092 (2d Cir. 1997) (approving of method of testing four randomly selected heroin balloons to estimate quantity of heroin contained in 103 balloons found inside defendant's body), with id. (disapproving of extrapolation from quantity of eighth trip that each of seven prior trips contained the same quantity). Thus, while quantities of controlled substances in a drug distribution conspiracy prosecution may be determined through extrapolation, approximation, or deduction, there ordinarily must be evidence of known quantities, which are sufficiently representative of the unknown quantities and from which an approximation of the unknown quantities can logically be derived. See Archer , 671 F.3d at 163.

Two of our decisions, though summary orders, provide a framework for understanding the role of representative proof in proving drug quantity. In United States v. Adames , the defendant was convicted at

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