The Fifth Circuit has deferred to the Board of Immigration Appeals’ determination that the personal use of marijuana exception to controlled substance deportability is subject to the circumstance specific analysis. Specifically, if the statute of conviction does not specify that the conviction involved less than 30 grams of marijuana, the adjudicator may consult other documents, such as the arrest report, to determine how much marijuana was involved in the offense.
The full text of Cardoso de Flores v. Whitaker can be found here:
http://www.ca5.uscourts.gov/opinions/pub/17/17-60744-CV0.pdf