The preamble is assuredly part of the instrument. We know this because the preamble was ratified.
Please read the whole thread or don’t bother to comment. Madison himself says it’s not. READ THE THREAD.
If you don't believe Madison [who was there, and it's been in all the papers] in support of your position, cite me an example in the Federal case law where The Preamble is used.
Oh, wait, you can't. Because the Supreme Court has never held such a position.
As a matter of fact, it has explicitly REPUDIATED the Preamble as part of the instrument:
Jacobson vs. Massachusetts, 1905:
Mr. Justice Harlan delivered the opinion of the court:
We pass without extended discussion the suggestion that the particular section of the statute of Massachusetts now in question ( 137, chap. 75) is in derogation of rights secured by the preamble of the Constitution of the United States. Although that preamble indicates the general purposes for which the people ordained and established the Constitution, it has NEVER been regarded as the source of any substantive power conferred on the government of the United States, or on any of its departments. Such powers embrace only those expressly granted in the body of the Constitution, and such as may be implied from those so granted. Although, therefore, one of the declared objects of the Constitution was to secure the blessings of liberty to all under the sovereign jurisdiction and authority of the United States, no power can be exerted to that end by the United States, unless, apart from the preamble, it be found in some express delegation of power, or in some power to be properly implied therefrom.
Read it, AND WEEP.
The Preamble is NOT part of the instrument. None of the founders ever believed it was, and neither does the case law support the contention.