When did Thomas Jefferson say If a law is unjust a man is not only right to disobey it he is obligated to do so?

Answer 1

The above quote is a paraphrase from the 5th sentence of the United States' Declaration of Independence:

But when a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new Guards for their future security.

Jefferson, Thomas. The Declaration of Independence. 1776. Retrieved from http://www.archives.gov/exhibits/charters/declaration_transcript.html on 15 March 2012.

Most of Jefferson's text was "borrowed" from john Locke's Second Treatise on Government, with the above from Section 225 of Locke's essay:

Secondly, I answer, such revolutions happen not upon every little mismanagement in public affairs. Great mistakes in the ruling part, many wrong and inconvenient laws, and all the slips of human frailty, will be born by the people without mutiny or murmur. But if 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; it is not to be wondered, 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.

Locke, John. Two Treatises Of Government. London, England, 1689. Retrieved from http://files.libertyfund.org/files/222/0057_Bk_SM.pdf on 15 March 2012.