Blackwater USA, a private security company, is undergoing unprecedented scrutiny following the shooting deaths of 17 Iraqis earlier this year. The investigation has revealed that this was only the most recent in a string of incidents that demonstrates horrific indifference to the violence perpetrated by private security firms in Iraq and a striking lack of oversight of their activity. The growing role of such firms is a fact of life in war zones, but policy and law have not kept pace with this new reality. The gaps must be filled.

There are huge numbers of private contractors in Iraq. In fact, those workers outnumber the 160,000 U.S. military personnel in the country. They do a wide range of logistical work, from driving trucks to cleaning facilities. Estimates of the number of private security contractors — those bearing arms — range from 13,000 to 30,000, and the majority of them are Iraqis. For the most part, they guard convoys and protect diplomats, business people and other foreigners.

The resort to private contractors is not new. The United States relied on privateers, private ships licensed to carry out warfare, to fight the British in the American Revolution and the War of 1812. The British issued letters of marque, which licensed pirates to fight London's rivals during the glory days of the empire.