¶21 …. The legislature has the authority to designate a prior conviction as a penalty enhancer rather than an element of the offense. Almendarez-Torres, 523 U.S. at 246. Although the legislature is permitted to designate a prior conviction as a penalty enhancer, it does not follow that the legislature is forbidden from designating a prior conviction as an element.  Unless otherwise designated by the legislature, a fact relevant to conviction is presumed to be an essential element of a crime. 
In short: “Determining whether a fact is an element or a penalty enhancer is an exercise in statutory interpretation,” ¶22. Of course, this potentially means review of extrinsic sources as well as the statutory text, but in view of the presumption the court has just announced, you’d think that there must be expressly declared intent to make the “fact” an enhancer, else by default it’s an element. While the outcome is adverse to the immediate litigant, Warbelton, to some extent it is simply a response to Apprendi-related caselaw developments, which the court usefully generalizes as: “a fact must be submitted to a jury and proven beyond a reasonable doubt if it increases the potential penalty for a crime beyond the penalty which could otherwise be imposed,” ¶20. Presuming that a penalty-increasing “fact” is an “element” greatly reduces the chances of Apprendi-type error, because it greatly increases the odds that the fact will indeed be submitted to the jury. That said, when it gets around to scrutinizing the statute, the court hardly relies on the presumption (indeed, doesn’t so much as mention it), but instead undertakes detailed analysis of both legislative history as well as text of the stalking legislation, ¶¶26-40.
Interesting discussion, in U.S. v. O’Brien, 1st Cir No. 07-2312, 9/23/08, on “this new algorithm,” noting as a complicating feature: “Congress in enacting complex criminal statutes rarely considers explicitly whether some designated fact should be deemed an element or a sentencing factor–a distinction, after all, primarily of concern to courts in administering the statutes.” And doesn’t that distinction reinforce the Warbelton presumption?