Fans of the 1960s television situation comedy "Hogan's Heroes" will, no doubt, never forget the signature line of the hapless Sgt. Schultz.

"I know nothing, NOTHING," he would state in response to any sign of trouble.

No one, of course, took Schultz's defense seriously. His earnest but unconvincing denials were played for laughs.

Oh, how times have changed. The "I know nothing" defense still is invoked, but now with the utmost seriousness in instances of corporate crime by officers far above Sgt. Schultz's pay grade.

Indeed, in late January or early February, assuming the trial begins as scheduled, former Enron chairman Ken Lay will become the latest top corporate officer to claim that he had no idea what was going on in the company he was paid many millions of dollars to run and that he was shocked – shocked – when he discovered things were amiss.

The tactic used by highly paid criminal defense lawyers is called the "idiot" defense. But whatever the title, it boils down to one claim – since I was unaware of any impropriety I'm not guilty of any criminality.

It's a tough defense to sell to a jury. Corporate officers at Adelphia and WorldCom were convicted despite their claims of ignorance of financial malfeasance that bankrupted their companies. But Richard Scrushy, the top man at HealthSouth, walked free after a slew of his subordinates pleaded guilty, were sentenced to prison and testified against him.

Now Lay and former Enron executive Richard Skilling are preparing to blame subordinates and claim they were left out of the loop. Their position, however, has been complicated by the recent decision of a co-defendant Richard Causey, a top Enron accountant, to plead guilty and testify rather than go to trial.

Enron's collapse marked the largest corporate bankruptcy in history, one that cost company employees and investors many billions of dollars. It's hard to imagine how the complex series of misdeeds that contributed to its collapse could have escaped the attention of top managers. Then again, that will be up to a jury to decide.