Gorsuch explained it this way:
As this Court explainedlong ago in Blockburger v. United States, “where the same act or transaction constitutes a violation of two distinct statutory provisions, the test to be applied to determine whether there are two offenses or only one, is whethereach provision requires proof of a fact which the other doesnot.”13 So if two laws demand proof of the same facts to secure a conviction, they constitute a single offense under our Constitution and a second trial is forbidden.

