Consider a few facts: Donald Trump is in the White House, despite winning almost three million fewer votes than Hillary Clinton. The Senate, the country’s most powerful legislative chamber, grants the same representation to Wyoming’s 579,315 residents as it does to 39,536,653 Californians. Key voting rights are denied to citizens in the District of Columbia, Puerto Rico and other United States territories. The American government is structured by an 18th-century text that is almost impossible to change. These ills didn’t come about by accident; the subversion of democracy was the explicit intent of the Constitution’s framers. For James Madison, writing...