The U.S. Constitution was in many ways modeled on the British government, which was in turn modeled on the Roman republic, and perhaps our founders' goal, like the Brits' goal and like Rome's goal, was to create a government that blended monarchical, aristocratic, and democratic elements. In our federal government, the Presidency is supposed to represent the monarchical, the Senate the aristocratic, and the House of Representatives the democratic elements.
It occurred to me recently that whether this bit of historical speculation is true, the three branches of the U.S. federal government provide a real-world example of the three main kinds of ethical philosophies in action. Congress generally works on some kind of utilitarian basis, although examples abound to the contrary. However, the general logic of institution is to weigh competing interests and find compromises that benefit the greatest number (and thus get majority support). The Presidency, as an institution, must be grounded in a virtue-based ethical philosophy. The Presidency was set up to deal with crises needing immediate action and unitary leadership: economic panics, wars, natural disasters, etc. Exigent and unique circumstances impede the President from using a deliberative, majoritarian process and also from using a process where he or she strictly follows a predetermined set of rules of ethical actions. We're left to hope that the President acts in good faith.
This leaves the judicial branch. The Supreme Court and the appellate courts operate on a kind of deontological basis. Granted, they're not Kantians. But the role of Constitutional interpretation involves a very similar kind of reasoning: the justices start with a first principle (the Constitution, rather than the categorical imperative); they apply this principle to real-world dilemmas by a hierarchy of values (e.g., whether the commerce clause or states' rights is more important) and distinctions (e.g., whether there is a difference between a tax penalty for not buying insurance and other taxes). The question of a limiting principle would make immediate sense to Kant, who seems to have struggled with limits on truth-telling, for example. It makes sense that the judicial branch would be filled with a kind of deontologist (should we call them Constitutional deontologists?), given that the primary purposes of the courts are justice (due process and due punishment) and, more broadly, justice (i.e., whether the laws themselves are just).
Using the branches of government as a model for kinds of ethical philosophies gives students something to latch on to. It gives the students a rough empirical basis for imagining the different thought processes and considerations that occur within each ethical philosophy: "Oh, just like Congress weighs the needs of Texas against those of all Americans." It especially helps them understand deonotology as an absolutist, first-principle-based philosophy, even though the first principle is different. The most important benefit of using the branches of government as a model is that students realize that an ethical philosophy is a framework, not a script. Just as Congress disagrees, so do utilitarians. Just as deontologists reach different conclusions, so do the Justices.