Here’s an interesting discussion of some background to the ‘mysterious’ 9th Amendment to the current U.S. Constitution. To it I would add that one might also look to the history of (other) rights in English Common Law, as well as of the Royal Prerogative (in 1776 theoretically arrogated to “the people” under the Republic, though pretty much there by now in England too, while remaining under Her Majesty’s Sovereign authority and ultimate responsibility and protection).
I would also caution that the writer seems to tread close to anti-government kookery at times, so take him with a grain of salt.
ALSO, some documents further discussing the Prerogative Writ of Quo Warranto, which may be usable against (ostensible) government and business officials and their acts. (Though if some Loyalist had used them against some of the usurping colonial governments in 1776 that website might have a somewhat different savor! If mere force majeur wasn’t allowed to prevail by the usurpers or their [few] supporters, anyway….)