In a letter to the editors of the Wall Street Journal appearing in today's edition, Professor Ronald L. McKinnon of Stanford University writes about the "currency wars," in which governments can manipulate the external value of their currencies by their choices in setting domestic monetary policies. In his view, the U.S. Federal Reserve has been the "leading manipulator" of the world dollar standard by setting interest rates at such low levels that "hot money" flooded to other countries — especially emerging markets — in search of better returns. According to Professor McKinnon, this happened in late 2002 when the Fed cut the federal funds rate to just 1 percent, sending U.S. dollars off to countries such as China and Brazil. The U.S. dol...