Imagine Congress enacts a law making it a federal crime to possess a knife in a local playground. When this law is challenged as beyond is Commerce Clause power, the federal government argues that the regulated activity (bringing a knife to a playground) substantially affects interstate commerce because it makes violent crime more likely, and this in turn discourages interstate travel, and the commercial activity tourists bring, to places where such crime occurs. Will this argument suffice to show that the activity affects interstate commerce?
