Thomas Jefferson, in writing the Declaration of Independence, and the authors of the U.S. Constitution were heavily influenced by the political theories of John Locke (1632-1704), which advanced the notion of constraints on government and the rights of the people to resist tyranny. Jefferson's reference to "life, liberty, and the pursuit of happiness" owes a great deal to the political philosophy of Locke. No one, however, should believe that the bar Locke set for legitimate violent resistance to legitimately-established government was set low. Locke realized that mere disgruntlement with government policies that did not infringe fundamental rights was insufficient to justify armed revolt. So long, he believed, the people had legitimate established avenues for addressing grievances, there was no legitimate ground upon which to act in a rebellious manner. As he wrote in his Second Treatise,
“The Reason whereof is plain; because the one using force, which threatned my Life, I could not have time to appeal to the Law to secure it: And when it was gone, 'twas too late to appeal. The Law could not restore Life to my dead Carcass: The Loss was irreparable; which to prevent, the Law of Nature gave me a Right to destroy him, who had put himself into a state of War with me, and threatned my destruction. But in the other case, my Life not being in danger, I may have the benefit of appealing to the Law, and have Reparation for my way.”
Absent satisfactory avenues through which to seek redress, however, the right of the people to rebel against its government is firmly established. A governing regime or structure that acts without the consent of the public, and that insulates itself from the public it purports to represent has lost its right to rule. The more repressive that governing structure, the more legitimate the effort to overthrow it. Again, quoting from the Second Treaties:
“Men can never be secure from Tyranny, if there be no means to escape it, till they are perfectly under it: And therefore it is, that they have not only a Right to get out of it, but to prevent it. . .[I]f a long train of Abuses, Prevarications, and Artifices, all tending the same way, make the design visible to the People, and they cannot but feel, what they lie under, and see, whither they are going; 'tis not to be wonder'd, that they should then rouze themselves, and endeavour to put the rule into such hands, which may secure to them the ends for which Government was at first erected; and without which, ancient Names, and specious Forms, are so far from being better, that they are much worse, than the state of Nature, or pure Anarchy; the inconveniencies being all as great and as near, but the remedy farther off and more difficult.” [http://press-pubs.uchicago.edu/founders/documents/v1ch3s2.html]
To reiterate, Locke made very clear that the right of the people to rebel against its ruler(s) was contingent upon a pattern of behavior by the ruler(s) that violated the fundamental rights of the people – the protection of their “Estates, Liberties, and Lives.” A government unresponsive to the will of the people it represents, or over whom it governs, has sacrificed its right to continue to rule. If the only way for the public to protect its liberties is through violent rebellion, then such action is legitimate.