The conviction of Ken Lay and Jeffrey Skilling is the successful culmination of a legal strategy Department of Justice prosecutors have been fine tuning since the day, in 2001, when Enron, one of America’s most respected companies, collapsed under the weight of a massive fraud.

That strategy called on law enforcement officials to indict and seek the conviction of chief executives of companies on fraud charges – often involving complex accounting schemes – even if there was little or no solid evidence that the executives intended to commit a crime or even knew the fraud existed.