Much has been written about the American International Group Inc., having run a risky credit default swap business out of its London office. That shop insured all sorts of financial products and bet that the bill would never come due. When it did, the company nearly crashed, and it has been a ward of U.S. taxpayers since last autumn.

What’s less well known is that, during this period, the global insurer was operating under the supervision of a U.S. Department of Justice-imposed monitor, whose job was to keep the company out of securities trouble.