Objective facts—while perhaps always elusive—are now an endangered species. A mix of digital speed, social media, fractured news, and party polarization has led to what some call a “post-truth” society: a culture where what is true matters less than what we want to be true. At the same moment in time when “alternative facts” reign supreme, we have also anchored our constitutional law in general observations about the way the world works. Do violent video games harm child brain development? Is voter fraud widespread? Is a “partial-birth abortion” ever medically necessary? Judicial pronouncements on questions like these are common, and— perhaps more importantly—they are being briefed by sophisticated litigants who know how to grow the factual...