The Heller decision on prefatory clauses:
The Second Amendment is naturally divided into two parts: its prefatory clause and its operative clause. The former does not limit the latter grammatically, but rather announces a purpose. . . Although this structure of the Second Amendment is unique in our Constitution, other legal documents of the founding era, particularly individual-rights provisions of state constitutions, commonly included a prefatory statement of purpose. . .
Logic demands that there be a link between the stated purpose and the command. The Second Amendment would be nonsensical if it read, “A well regulated Militia, being necessary to the security of a free State, the right of the people to petition for redress of grievances shall not be infringed.” That requirement of logical connection may cause a prefatory clause to resolve an ambiguity in the operative clause (“The separation of church and state being an important objective, the teachings of canons shall have no place in our jurisprudence.” The preface makes clear that the operative clause refers not to canons of interpretation but to clergymen.) But apart from that clarifying function, a prefatory clause does not limit or expand the scope of the operative clause. . . “ ‘It is nothing unusual in acts . . . for the enacting part to go beyond the preamble; the remedy often extends beyond the particular act or mischief which first suggested the necessity of the law.’ ”
With this enlightening footnote:
JUSTICE STEVENS says that we violate the general rule that every clause in a statute must have effect. . . But where the text of a clause itself indicates that it does not have operative effect, such as “whereas” clauses in federal legislation or the Constitution’s preamble, a court has no license to make it do what it was not designed to do. Or to put the point differently, operative provisions should be given effect as operative provisions, and prologues as prologues.
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