What is the legal test for possession of a small amount of marijuana under the International Narcotics Control Act?

The BIA in Castro Rodriguez located support for its 30-gram figure in a possession subsection of the INA that exempts from the definition of a "controlled substance" offense the possession of "30 grams or less of marijuana." 8 U.S.C. 1227(a)(2)(B)(i). Section 1227(a)(2)(B)(i) of the INA and 21 U.S.C. 841(b)(4) share a similar function within their respective statutory schemes: each serves as a reference point for the immigration consequence of a state drug conviction. See Mellouli v. Lynch, U.S. , 135 S.Ct. 1980, 1984, 192 L.Ed.2d 60 (2015) (explaining that a noncitizens state conviction is not a deportable offense if the state statute punishes conduct defined by 8 U.S.C. 1227(a)(2)(B)(i) ). So, as a matter of statutory construction, there is some force to assigning 30 grams as a benchmark "small

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amount" to align the treatment of marijuana quantities in the CSA to the INA. Cf. FDA v. Brown & Williamson Tobacco Corp., 529 U.S. 120, 133, 120 S.Ct. 1291, 146 L.Ed.2d 121 (2000).