For public companies, investigations of possible stock-option backdating have become a huge headache. But for big law firms, they're the latest full employment act, generating hour after billable hour of work across practice areas, from tax and executive compensation to securities and white-collar defense. Big law firms have traditionally tilted their practices to capitalize on the business topic of the day, from the M&A wave in the 1980s to the post-Enron and WorldCom bankruptcy boom. But the backdating scandal "is fairly unique in its complexity and scope and how many clients it touches and how serious and important it is ... .