Despite its many faults, the United States Constitution, which became effective thirteen years after the Declaration of Independence, shows the continuing influence of the liberal natural-rights doctrine, particularly in its first ten amendments, known as the Bill of Rights and ratified in 1791. Consider, for example, Amendment IX: "The enumeration in the Constitution of certain rights shall not be construed to deny or disparage others retained by the people." This language makes sense only if we assume that certain rights exist prior to the Constitution and thus prior to any governmental recognition, i. e., as natural rights. Without an understanding of natural rights, Amendment IX seems nonsensical, and for this reason it has been largely ignored in modern times. More generally, there is ample evidence that the framers of the Constitution were strongly aware of the danger that the new government might become invasive of the very rights it was intended to secure; consequently, they provided many mechanisms to limit the power of government and to discourage the hasty passage of unnecessary laws.

Unfortunately, the Constitution as of 1791 was already riddled with flaws and moral compromises, which led eventually to the reversal of many of the liberal ideas on which it was based. Such compromises, as will become clear later in this section, create a very strong tendency for governments to become increasingly invasive of human freedom over time. The most conspicuous of these compromises, of course, was the acceptance of slavery, and the failure of Jefferson and the other founders to renounce that institution not only obscured the liberal roots of their philosophy but also contributed enormously (if largely indirectly) to the reactionary return of statism in the nineteenth and twentieth centuries (cf. pp. 3.10:13-5).