The historical background of [the immigration provision in question] demonstrates that Congress and the [Board of Immigration Appeals] have long required a direct link between an [immigrant]’s crime of conviction and a particular federally controlled drug. The Government’s position here severs that link by authorizing deportation any time the state statute of conviction bears some general relation to federally controlled drugs.
The Government offers no cogent reason why its position is limited to state drug schedules that have a “substantial overlap” with the federal schedules… . This sweeping interpretation departs so sharply from the statute’s text and history that it cannot be considered a permissible reading.
We therefore reject the argument that any drug offense renders an [immigrant] removable, without regard to the appearance of the drug [in the federal controlled substance law].
Mellouli v. Lynch, 575 U. S. ____ (2015) (majority opinion) (citations omitted).