Today the U.S. Supreme Court overturned the conviction of accounting firm Arthur Andersen for shredding paperwork involving Enron, unanimously ruling the instructions to a Houston jury were flawed.

This week's decision by accounting firm KPMG to admit criminal wrongdoing and pay a $456 million penalty raises a couple of pertinent questions: What took the firm so long? And how could it have engaged in such rotten conduct to begin with?