The preoccupation with independent directors under Sarbanes-Oxley is misguided, says Wayne State University law professor Erica Beecher-Monas. After all, Enron and WorldCom had independent directors and look what happened to them.

In her study, Marrying diversity and independence in the boardroom: Just how far have you come baby?, she argues that independence defined as an absence of conflicting interests does not go far enough.

Directors function as a small social network, a little exclusive club, so what's needed independent thought and active, open-minded thinking on such issues as hiring and firing the chief executive, setting executive pay, granting stock options and approving conflict of interest transactions. And the problem with having an exclusive club, she says, is that it squashes dissent and stops people asking hard questions. Her study cites evidence showing that boards with more diverse membership were better placed to handle internal conflict of interest guidelines.

Only 11 per cent of corporate directors in the US are women and only 7 per cent being minorities so if her argument is right, corporate governance problems are not going to go away.

"As long as directors come from the same narrow pool of socially tied and ethnographically indistinguishable people, it will be difficult to achieve the range of experience and perception that goes into active open-minded thinking,'' she writes."Nourishing a culture of dissent requires respect for differences.''

The paper gives plenty of food for thought. Certainly, independence of directors is not the panacea it's cracked up to be. There have been at least 50 academic studies on whether having more independent directors goes with financial performance. The empirical evidence is at best inconclusive. Several studies have come up with correlations that range from positive to negative, and others show that independence has no observable effect.

So by any objective analysis, pointing to any clear trend one way or the other is impossible.