PHOTO: MITCH EPSTEIN/BRYAN CHRISTIE DESIGN

One smart operator: Alert controllers at the New England Independent System Operator in Holyoke, Mass., saw the August 2003 outage coming and were able to disconnect their region in time to keep the lights on.

In his classic book Normal Accidents: Living With High-Risk Technologies (Basic Books, 1984), the sociologist Charles Perrow describes a day when everything just goes wrong. You lock yourself out of your house, leaving your car keys inside. The spare, normally hidden, house keys have been lent to a friend, and your alternate ride, a neighbor's car, is in the shop. A strike has shut down metropolitan bus services, swamping the taxi fleet. On and on goes the litany, and in the end, you miss an important meeting. Perrow then challenges the reader to name the cause of the foul-up. The answer, of course, is everything and yet no one thing.

Perrow calls this a "normal accident," because there's no way to foresee all the things that might go wrong. One could resolve never to let the same mishaps strike again, but the safeguards would come at a cost and could not protect against all possibilities. You could go ahead and stash extra keys, yet still miss your meeting because your neighborhood is cut off by mud slides. Systems are prone to such accidents, Perrow argues, in proportion to their complexity and "tight coupling": one problem causes others, like the bus strike's overburdening the taxi service.

Arguably, the most complex and tightly coupled systems ever constructed for use in daily life are those making up the interconnected electric power grid, which is by its nature vulnerable to system accidents. When such accidents are rife, they must be regarded as the symptom of inadequate grid design and management, itself a product of a bad system of incentives. Tellingly, expert groups investigating Italy's nationwide blackout of 28 September 2003 and the northeastern North American blackout of 14 August 2003 reached very similar conclusions about their underlying causes. What is more, if recommendations made following the three major western North American blackouts between 1994 and 1996 had been followed, the effects of the 2003 outages would have been far less severe.

These events underscore the urgency of adopting enforceable measures to reduce the frequency and impact of massive grid outages. The U.S. Energy Policy Act of 2005 gives a self-regulating electric power organization, subject to review by the Federal Energy Regulatory Commission, the authority to enforce reliability rules and regulations. That organization will be the North American Electric Reliability Council (NERC), a multinational council based in Princeton, N.J., Separately, Mexican and Canadian authorities have promised to back NERC's regulations with the force of law.