True to the liberal tradition, then, Kant regarded the fundamental task of government as negative, as imposing those constraints that are necessary to protect and promote each person's freedom. The legal system of the state must constrain both the power of the sovereign and the citizens' unregenerate desires in order to establish the conditions under which people can live together in peace as a community. The basic laws of the legal code therefore should set out negative obligations, duties prohibiting people from interfering with the freedom of their fellow citizens. (Few terms have more importance than "duty" in Kant's political theory, and, as we shall see, in his ethical theory as well.)
For Kant, then, the most basic function of civil law is not to grant entitlements but to lay down obligations. Whatever the benefits arising from living in the state, Kant believed that citizenship should be construed as a task, a responsibility to contribute to those moral conditions necessary if political security and order are to endure and flourish. By contrast, rights are derivative: they arise only from corresponding duties that the state enforces.
(Roger J. Sullivan, An Introduction to Kant's Ethics [Cambridge: Cambridge University Press, 1994], 10-1 [italics in original])
