The Supreme Court overruled the Ninth Circuit's en banc decision on the categorical analysis of criminal convictions in United States v. Aguila-Montes de Oca. The categorical analysis refers to the process of comparing a prior state or federal conviction to a generic federal definition of a crime to determine whether the prior conviction triggers certain consequences. The Supreme Court held that a court may look to the record of conviction (charging document, plea transcript, jury findings, etc.) only if the defendant was convicted of a “divisible” statute and resort to the record is necessary to determine which of separate alternative elements that the conviction rested on. In contrast, if a statute is not divisible—meaning it contains a single set of elements that is broader than the generic offense—the categorical inquiry is resolved in the defendant’s favor, even if he actually committed the generic offense or admitting to doing so.
My own example based on the holding is as follows: if a statute penalizes possession of cocaine, heroin, or marijuana (and if the identity of the drug is relevant to the federal generic definition), then the reviewing court can look to specified documents from the record to determine if the conviction was for cocaine, heroin, or marijuana. On the other hand, if the statute penalizes possession of unspecified drug paraphernalia, then the reviewing court may not be look to the record to determine the drug that the paraphernalia related to, since the identity of the drug is not an element of the offense.
In Aguila-Montes de Oca, the Ninth Circuit had held to the contrary that a reviewing court may look beyond the elements of a conviction to assess the purported facts of a case based on the prosecution's theory of the crime. For example, pursuant to that opinion a reviewing court could look to other evidence, such as an arrest report, that the paraphernalia had residue of heroin. The Supreme Court not only rejected that approach, but disparaged it. It held that "accepting the Ninth Circuit’s contrary reasoning would altogether collapse the distinction between a categorical and a fact-specific approach." And there are several parts of the Supreme Court's opinion that are more caustic than that, making for a good read.