The answer is a very big deal to Marcus Sykes, whose Supreme Court challenge — Sykes v. U.S. — will be argued Jan. 12. And how the justices get to that answer is an equally big deal for criminals facing tough sentences and for courts struggling to determine what constitutes a violent crime under the law.

The justices have issued seven Armed Criminal Career Act — or ACCA — decisions in the last five years, and it doesn’t appear that the flow of cases in the lower court pipeline will ease any time soon.