In this masterful essay, Thoreau elaborates on his decision to refuse to pay taxes to support a war in Mexico that he saw as unjust and completely wrong. This essay therefore explores the nature of government and also the responsibility of citizens within a government to ensure that democracy is upheld. Thoreau in this essay argues that it is the citizen's duty to practise civil disobedience when doing the alternative (obeying the law) would cause you to be responsible for committing a crime against another person. Note how he elaborates on this point:
...but if it is of such a nature that it requires you to be the agent of injustice to another, then, I say, break the law. Let your life be a counter friction to stop the machine. What I have to do is to see, at any rate, that I do not lend myself to the wrong which I condemn.
In Thoreau's opinion, therefore, it is the duty of every citizen to practice civil disobedience in order to point out to the government when their policies and laws are actually injust and should be changed. Thoreau believes that everyone has the responsibility to make sure their actions are not "the agent of injustice to another." If by following a law this occurs, then citizens have a responsibility to break that law. This is of course a very contentious issue, but broadly Thoreau's arguments have been supported by a number of critics and thinkers. The key issue to debate is how one determines whether a law makes a mere citizen the "agent of injustice to another." This relative truth is of course impossible to determine in many cases.