How does a nation ensure that in several generations its government will pursue current values.

I'm reminded of the openining of Leviathan, which sounds like it's about AI, but is actually about government: "For what is the heart, but a spring; and the nerves, but so many strings; and the joints, but so many wheels, giving motion to the whole body, such as was intended by the Artificer? Art goes yet further, imitating that rational and most excellent work of Nature, man."

The things that can go wrong with an AI (behaving in accordance with the rules as written instead of the will of the designer) even resemble things that can go wrong in a legal system.