"The Christian Magistrate: a Discourse, with an Appendix" by Thomas Houston, a Covenanter, is a defense of theonomy written in 1832. It covers such things as the supremacy of Christ and the sufficiency of Scripture in political matters, ruler qualifications, the duties of civil magistrates, and the historical Reformed perspective on civil government.
It can be downloaded or read online here.
The moral law defines and declares the crime, but says nothing of the punishment. The Judicial law is the fence that God himself set round the precepts of the Decalogue, which are of universal obligation. It is the penal code of heaven – the rule by which alone, as far as human society is concerned we can measure the magnitude of the crime committed, [p. 90] and the proper award of punishment which it merits. Consider it entirely abrogated, and then, as far as relates to the Civil Magistrate, the sanction of the Decalogue is removed. He has a sword still, but he is without directions how he may use it.
Like a mariner without a compass, he is afloat on a sea of uncertainties, ready at every moment to be swallowed up by the tempestuous billows, or to be dashed to pieces on the rocks and quicksands that threaten his destruction. But the Christian Magistrate is not appointed God’s minister, and left thus without directions in performing the functions of his arduous office. His duty is clearly and minutely declared in the words of Him who is without variableness and shadow of turning, and whose law, like himself, is unchangeable. With this divine instrument in his hand, he has nothing to fear. Let him apply it faithfully, and leave the consequences with God. Then will his administration be crowned with success, and God’s glory and man’s good will be extensively promoted. (pp. 90, 91)