Experts disagree with your assessment:
Although the preamble is not a source of power for any department of the Federal Government, 1 the Supreme Court has often referred to it as evidence of the origin, scope, and purpose of the Constitution. 2 ''Its true office,'' wrote Joseph Story in his COMMENTARIES, ''is to expound the nature and extent and application of the powers actually conferred by the Constitution, and not substantively to create them. For example, the preamble declares one object to be, 'to provide for the common defense.' No one can doubt that this does not enlarge the powers of Congress to pass any measures which they deem useful for the common defence. But suppose the terms of a given power admit of two constructions, the one more restrictive, the other more liberal, and each of them is consistent with the words, but is, and ought to be, governed by the intent of the power; if one could promote and the other defeat the common defence, ought not the former, upon the soundest principles of interpretation, to be adopted?''
From here. Arguably, making marijuana illegal is an effort by Congress to ensure domestic tranquility. Whether this is actually being accomplished, however, is a matter of some debate. I agree that making it illegal is of dubious effectiveness, but I disagree with your statement that they have no right to do so.
Beeblebrox.420 Reviewed by Beeblebrox.420 on . Supreme Court murders California man RIP Steve McWilliams...... Friends and supporters of McWilliams, who killed himself last week in a desperate effort to end his suffering and draw attention to his cause, will gather at City Hall at noon to remember the activist who pushed San Diego into becoming the largest city in the nation to adopt a medical marijuana law. http://www.unknownnews.org/0507190717McWilliams.html Rating: 5