The disparate approach to state drug convictions, devised by the BIA and applied by the Eighth Circuit, finds no home in the text of §1227(a)(2)(B)(i). The approach, moreover, “leads to consequences Congress could not have intended.” Moncrieffe, 569 U. S., at ___ (slip op., at 15). Statutes should be interpreted “as a symmetrical and coherent regulatory scheme.” FDA v. Brown & Williamson Tobacco Corp., 529 U. S. 120, 133 (2000) (internal quotation marks omitted). The BIA, however, has adopted conflicting positions on the meaning of §1227(a)(2)(B)(i), distinguishing drug possession and distribution offenses from offenses involving the drug trade in general, with the anomalous result that minor paraphernalia possession offenses are treated more harshly than drug possession and distribution offenses. Drug possession and distribution convictions trigger removal only if they necessarily involve a federally controlled substance, see Paulus, 11 I. & N. Dec. 274, while convictions for paraphernalia possession, an offense less grave than drug possession and distribution, trigger removal whether or not they necessarily implicate a federally controlled substance, see Martinez Espinoza, 25 I. & N. Dec. 118. The incongruous upshot is that an alien is not removable for possessing a substance controlled only under Kansas law, but he is removable for using a sock to contain that substance. Because it makes scant sense, the BIA’s interpretation, we hold, is owed no deference under the doctrine described in Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837, 843 (1984) .