(Photo: Shutterstock) W hat if we could save millions of lives, eradicate a contagious disease, and repair a structural defect in the U.S. economy, all by asking the question: What is reasonable? This question—put another way, What is just?—is at the center of a health-care initiative brewing in, of all places, Louisiana. If successful, it could eradicate hepatitis C and put a fatal crack in a drug-pricing system that systematically balloons costs and kills the sick. The word “reasonable” comes from a piece of federal law known as 28 U.S. Legal Code 1498. It establishes the government’s right to infringe on privately held patents, should doing so serve the national interest. The government, in return, is obligated to give the patent holder what the code calls “reasonable compensation.” As with eminent domain, the government determines “reasonable” by the specifics of the case. In the case of the gestating Louisiana initiative, the patent in question covers a grotesquely overpriced new...