I disagree with Thoreau's statement that civil disobedience is duty.
He made a good argument for his statement. He believe that the tax that we pay would be used by the government to buy weapons when they decided to be involved in a war and kill a lot of people. He believed that by not paying tax, he is doing a good thing because He does not want to be involved in the war in any way.
But, one thing that we need to consider is that Taxes also used to fund government welfare programs to help the fool. So I believe civil disobedience that Thoreau did could hurt others that actually need help.
I think one of the case when civil disobedience is justified is if the government transformed into an authoritarian that want to disregard the value of democracy.