SCOTUS finds, per Justice Scalia, that ACCA residual clause is unconstitutionally vague

In a very important Fifth Amendment criminal procedure ruling, though one certain to be overlooked because of an even more important Fourteenth Amendment ruling issued right before it, the Supreme Court this morning in Johnson v. United States, 13-7120 (S. Ct. June 26, 2015) (available here), ruled that a key clause of the Armed Career Criminal Act violated "the Constitution’s prohibition of vague criminal laws."  Justice Scalia wrote the main opinion for the Court (which carried five other Justices, including the Chief), and here is a key paragraph from the begining of the opinion's legal analysis:

We are convinced that the indeterminacy of the wide-ranging inquiry required by the residual clause [of ACCA] both denies fair notice to defendants and invites arbitrary enforcement by judges. Increasing a defendant’s sentence under the clause denies due process of law.

I will need some time to review and reflect to figure out how big a ruling Johnson may prove to be. But the basic reality that the defendant prevailed here on the broadest constitutional ground (and especially the fact that only Justice Alito was prepared to rule for the federal government on appeal) further proves a point I have been making since Blakely was handed down over a decade ago: The modern US Supreme Court is, at least on sentencing issues, the most pro-defendant appellate court in the nation.

That all said, and of particular significance for ACCA sentences that are built on convictions that do not depend on interpretations of the residual clause, the Court's opinion in Johnson ends with this critical and clear discussion of the limits of the holding:

We hold that imposing an increased sentence under theresidual clause of the Armed Career Criminal Act violates the Constitution’s guarantee of due process. Our contraryholdings in James and Sykes are overruled. Today’s decision does not call into question application of the Act to the four enumerated offenses, or the remainder of the Act’s definition of a violent felony.