From Jim: tax policy, trade policy, substantial portions of international policy, and drug policy.
Let me suggest that: a complex and steeply progressive income tax, trade barriers beyond very modest uniform tariffs, more activist and interventionist foreign policy and criminalization of drug activities are largely the result of our failure to adhere to the principle of limited government during the 20th Century.
"...statism, which my dictionary defines as the concentration of economic controls and planning in the hands of a highly centralized government, and which I further define as the belief that the state is the mechanism best suited for solving most if not all of society's ills, be they health related, natural disasters, poverty, job training, or injured feelings. Statism is the great political disease of the twentieth century, with Communist, socialist, and many democratic nations infected to a greater or lesser degree. When the political history of our century is written, its greatest story will be how a hundred variants of statism failed." Jim Rogers from Investment Biker