2scents:
It is, IMHO, one of the most fascinating and timely issues in halacha, and one that I have studied very intensely for years. If you look through Shailos U’Teshuvos of the Rishonim (especially, Rashba, Rosh, Maharam of Rothenburg, and Rivash, as well as other writings of the Ibn Ezra, Rambam, Mordechai; for more contemporary ways of dealing with these questions, see R. Herzog’s writings) you will discover that there are many, many different ways of approaching the topic. IMHO, to really understand the issues, you need to have a good grasp of political theory and the history of political thought. Many of the Rishonim who wrote on these issues had a very good grasp of politics, constitutionalism, and democratic and republican theory.