If only there were a scientific way to determine the real impact of taxation on industriousness, labor supply, and innovation.According to some scholars, there is. Randomly assign a representative sample of the population — say, 10,000 taxpayers — a lower tax rate, and see what happens. Did these Americans, on average, behave any differently than their counterparts? Did they work longer hours or more jobs, start more businesses, hire more employees?In other words, test government policies using the same technique — randomized controlled trials — used to test new drugs. A growing chorus of legal scholars, economists, and political scientists believes that such trials should be conducted to evaluate a wide range of laws: gun control, safety and environmental regulations, election reforms, securities rules, and many others. And some believe that we are ethically obligated to do this, because laws affect our lives so pervasively. Understanding the true costs and benefits of legislation, they say, is essential to making good policy — and we may know much less about our own laws than we think.