In business, the penalties for poor book-keeping can be severe. The first principle of accounts is that they should present, as far as possible, a fair and accurate picture of an organisation's financial position. That means not only reporting a year's income and expenditure, and listing current assets and liabilities, but also setting out future obligations and sources of revenue. Executives who ignore these precepts risk being hauled before the courts for deceiving investors. Yet for all the vigour with which America's politicians have denounced the country's recent corporate scandals, it is not clear that the government's books are any...