Since Scalia bases a good portion of his Second Amendment analysis in DC v. Heller on the first clause being "prefatory"--
Nelson Lund, for example, helped shift the focus of Second Amendment interpretation by characterizing its first clause as “prefatory” and its second clause as “operative” — and received a Second Amendment chair funded by the NRA for his work. A Hein Online search for the terms “operative,” “prefatory,” and “second amendment” suggests that Nelson Lund was the first academic to introduce this terminology into the Second Amendment literature. See Nelson Lund, The Past and Future of the Individual’s Right to Arms, 31 GA. L. REV. 1 (1996). Nelson Lund is the Patrick Henry Professor of Constitutional Law and the Second Amendment at the George Mason University School of Law. This position was created thanks to a one million dollar commitment to GMU School of Law by the National Rifle Association Foundation announced in 2003. Press Release, $1 Million Endows Professorship at George Mason University (Jan. 28, 2003). Justice Scalia relies on the distinction between “prefatory” and “operative” in describing the relationship of the amendment’s first and second clause. See, e.g., Heller, 128 S.Ct. at 2789 (“The Second Amendment is naturally divided into two parts: its prefatory clause and its operative clause.”).
The problems is that, as has been pointed out, Scalia also uses Blackstone's commentaries on the Laws of England and is bound by the language of Marbury v. Madison, 5 U.S. (1 Cranch) 137 (1803):
The subsequent part of the section is mere surplusage, is entirely without meaning, if such is to be the construction...It cannot be presumed that any clause in the constitution is intended to be without effect; and therefore such construction is inadmissible, unless the words require it.
Blackstone would look to the proeme (the "prefatory clause") for guidance in interpreting the language (see previous post and this).
So, the idea of "prefatory" and "operative" came about over 200 years after the drafting of the Bill of Rights (1996).
Hardly original.