From monticello.org
When injustice becomes law, resistance becomes duty.
This statement has not been found in Thomas Jefferson's writings, although it captures some of the ideas that Jefferson expressed in the Declaration of Independence, e.g. "...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..."
- Anna Berkes, 4/11/13
First attribution of the above quote was 2006. I like the "tyranny" substitution.