Quite a lot of the western world had capital controls during parts of the 20th century. With many G20 economies now burdened by debt, collapsing tax revenues, and a socialist mind-set, there is the real prospect of major capital flight out of the weaker countries. How long before a western government decides to get rid of the problem by imposing capital controls? This is a serious risk for traders, since it could prevent you taking your money out of the country - no trading on foreign markets, no avoiding punitive taxes by moving abroad with your money. You would become a de facto economic slave, with a financial iron curtain descending around the national borders.