Sure, we all pay lip service to the Madisonian system of checks and balances. But as one legal scholar argues, presidents have been running roughshod over the system for decades. The result? An accumulation of power that's turned the presidency into a position the founders wouldn't have recognized.

To you, it's just a ride-sharing app that gets you where you're going. But to an economist, Uber is a massive repository of moment-by-moment data that is helping answer some of the field's most elusive questions.