The ideas in Lex Rex predate modern concepts of nationalism and politics. They are older than the United States Constitution, as well as the American Revolution - where many modern ideas of liberty originated. Lex Rex is even older than the Enlightenment that receives so much credit for concepts such as popular sovereignty, limited government, separation of powers, and individual liberty. Nevertheless, Samuel Rutherford's Lex Rex - written at a time that viewed kings as vessels of divine power - raised a Scriptural standard arguing for the dignity of the people and the accountability of earthly governments. Although some would seek to pigeonhole the book as merely a tract on civil resistance, Lex Rex contains a comprehensive examination of a Christian view of civil government. In doing so, Lex Rex actually formulates a blueprint for freedom applicable for any time and any place. Rutherford hoped to demonstrate the need for government based on law instead of the arbitrary decisions of fallible humanity. Throughout this process, the Bible is the final authority and basis for law. This Scriptural base was a primary reason for both the great support and opposition that met Lex Rex.
If we are assuming that the government must be based on the system used in the Old Testament, this is probably really good. But, I'm not assuming that. I have no reason to think that God wants every nation to follow the governmental patterns laid out in Deuteronomy.
A few really odd things in this book, one example being that non-resistance is laid out as being essentially the same as suicide.
I also think this edition of the book, may not be the best version possible. There were several typographical errors.
Probably a good resource if you want to reconcile faith with politics. I have no interest in the latter so it was of limited use to me. I also found it a difficult book to follow and much harder than other Puritan books I have read. This may well be due to my general disengagement with the subject matter.
Sort of an abridgment of Rutherford's excellent work, but the abridgment seems more wooden and disconnected. Rutherford's ideas were critical to seeing the role of the people and their responsibility regarding their ruler, many of the ideas which would lead to the justification for the American Revolution.