Something I was thinking about earlier, there are more people alive today in the position to destroy the entire planet than ever before. There was a time when the amount of damage one man could inflict was limited by his armies, but now the amount of creative/destructive power possessed by individuals is growing. One man, if properly prepared and outfitted could lay waste to millions of people, and the number of people capable of such a thing will only grow as technology advances. That doesn't even take into account more 'sophisticated' forms of destruction like biological warfare, economic destruction and cyberwarefare. There will come a day in the middle/far future when every member of our society will hold the power to destroy every other member of society (Or at least massive portions) and they must actively choose not to. How do you govern such a group? How do you control anything about them? For a more specific example think of it like this. Give every legal adult citizen in the US enough nukes to destroy the entire country, how long does the country last?
I propose this for the sake of argument and with the assumption that things like small-scale nuclear devices, 3d printing and molecular engineering will become highly personal or at least highly accessible.