The United States is the global leader in medical innovation. You can measure that by Nobel Prizes or biotech R&D or where breakthrough treatments are developed or commercialized. And as University of Michigan economist Miles Kimball points out, one reason healthcare spending is lower in other advanced economies is their ability to “ cheaply copy drugs and medical techniques developed in the US at great expense.” But healthcare innovation isn’t just about miracle drugs and cutting-edge technology. Innovation can happen in how healthcare services are delivered and paid for. And it is in this area that the Affordable Care Act...