The obvious rebuttal to that particular comment is the Late, unlamented 18th Amendment to the Constitution. While the elected representatives voted in favour of it (as well as the elected representatives of the several states that ratified it), it did not have popular support of the very people who the congress and state legislatures supposedly represented.
So just who were these US Senators, US Representatives, State Senators, and State Representatives actually representing? That's right Skippy, they were representing wacko moralists and lobyists who were screaming the loudest, (and undoubtedly donating to campaigns). On a side note: i find it funny that these same wacko moralists were holding the substance responsible for the behaviour, rather than the individual who consumed it, even though the vast majourity of the American people who did consume that particular substance did not have any such problems with the use of that substance.
If you aren't comfortable with that particular parallel...and drugs are just a SMALL part of Libertarianism...let's go on to something else.
At one time most states had laws on the books that forbid interracial marriage. Would couples of differing races who did marry in other locations be committing a crime by the very existence of their marriage? This is a perfect example of government ARBITRARILY making otherwise law-abiding citizens into criminals by nothing more than statutory fiat.
My final point on this issue is that the constitution of the US exists in order to memove the "tyranny of the majourity" that a democracy causes. It's interpretation is a relatively simple matter..."If it ain't in there, government ain't supposed to do it." The issue being that the vast majourity of what government is presently doing is unconstitutional, no matter who or how many representatives voted for it.
To them, the police power of 'majority will' is just a given principle.
Their faith in 'democracy' has no limit, just as their trust in our Constitutions republican principles is sorely lacking