That’s discouraging. Apparently, the­ anti-money laundering laws that many governments enacted after Sept. 11, 2001, have changed little. Indeed, according to Edwin Truman and Peter Reuter’s study for the Institute for International Economics, in the United States, where these new protections are most stringent, money launderers face only a 5 percent chance of being convicted in any given year. Anywhere else, the chances are even less.

Laundered money is, of course, not the only illicit international trade that governments are unable to stop. Despite a long-standing war on drugs, the total size of the global drug trade probably doubled between 1992 and 2002. For most of the 1990s, an average of 500,000 people crossed illegally into the United States each year. The hope was that the border controls enacted after 9/11 would make that number drop. It hasn’t. Half a million people are still entering the country illegally every year. The same is true in Europe, where tighter immigration controls have failed to yield any significant reduction in illegal immigrants.

Governments have failed to stop a wide range of illegal commerce. Fifteen years ago, the trade in pirated goods was almost insignificant. Today, it is valued at $400 to $600 billion a year. No insurgency anywhere in the world seems to have much difficulty procuring the weapons it needs, which is one of the reasons that the illegal arms trade is worth $10 billion. International human trafficking comes to another $10 billion. Stolen art, according to Interpol, is worth $3 billion a year. In the last decade, all of these illegal international trades have grown in size and scope.

The explosion of money laundering offers a glimpse of the total size of the world’s illicit economy. Money laundering has grown at least tenfold since 1990,...