text: luna objects to drawing that line on the ground that it is too hard to tell the difference between the two.see brief for petitioner discussing,in particular,statutes criminalizing the destruction of federal property and sending threats via the postal service.but that contention collides with the judicial experience just described.courts regularly separate substantive from jurisdictional elements in applying federal criminal statutes mens rea requirements so too in implementing other laws that require a comparison of federal and state offenses.and from all we can see,courts perform that task with no real trouble luna has not pointed to any divisions between or within circuits arising from the practice.we do not deny that some tough questions may lurk on the margins where an element that makes evident congress regulatory power also might play a role in defining the behavior congress thought harmful.but a standard interstate commerce element,of the kind appearing in a great many federal laws,is almost always a simple jurisdictional hook and courts may as easily acknowledge that fact in enforcing the ina as they have done in other contexts.