In a decision on criminal sentencing enhancements, the Supreme Court has clarified what qualifies as an "element" of a crime, as opposed to a "means" of committing a crime. "'Elements' are the 'constituent parts' of a crime’s legal definition—the things the 'prosecution must prove to sustain a conviction.' At a trial, they are what the jury must find beyond a reasonable doubt to convict the defendant, and at a plea hearing, they are what the defendant necessarily admits when he pleads guilty."
To determine if a fact is an element, an adjudicator may look to the statutory text, as well as state case law and jury instructions. The Court noted that if the statutory alternatives carry different punishments, they must be elements.
If these sources do not clearly answer the question, an adjudicator may look at certain documents in the record of conviction - such as the charging document - to determine the elements of the statute. Typically, any facts charged in the alternative in a charging document will NOT be considered elements. Conversely, an indictment and jury instructions could indicate, by referencing one alternative term to the exclusion of all others, that the statute contains a list of elements, each one of which goes toward a separate crime.
Most interesting perhaps is the Court's discussion of what an adjudicator should do if all of these sources do not shed light on whether a fact is an element or a means. "Of course, such record materials will not in every case speak plainly, and if they do not, a sentencing judge will not be able to satisfy 'Taylor’s demand for certainty' when determining whether a defendant was convicted of a generic offense." This reference to certainty suggests that any ambiguity regarding whether a fact is an element or a mean should be construed in favor of the criminal defendant (or the immigration petitioner). Notably, footnote 2 in the decision clearly states that the decision's analysis applies to immigration proceedings as well.
The full text of Mathis v. United States can be found here: