After all, the purpose of law enforcement is not simply to punish people for crimes they have committed, but to deter crimes that are being contemplated. That pushes prosecutors to send strong signals about the dangers of crossing the line by bringing cases that penetrate the public consciousness. If yesterday's indictment had been against Martha Jones rather than Martha Stewart, no one would be reading this article -- primarily because it would not have been written.

''The deterrent effect is immeasurable,'' said Christopher Bebel, a former lawyer with the Securities and Exchange Commission and a former federal prosecutor. ''Even if the government puts a thousand hours into building this case against Martha Stewart, the risk-reward ratio is enormously positive and constitutes a very prudent allocation of government resources.''

Even if the government fails to obtain a conviction, lawyers said, aggressive corporate executives -- having seen the price Ms. Stewart paid -- will be far more careful about even approaching the line that defines an obstruction of justice. With the prosecution of Ms. Stewart on that charge coming only a year after document shredding helped destroy the Arthur Andersen accounting firm, it would be hard for a corporate executive not to get the message.

The securities fraud count -- with Ms. Stewart effectively charged with defrauding the investors in Martha Stewart Living Omnimedia by publicly stating that she put in an order to sell ImClone shares at $60, a claim the indictment says is false -- the government has also sent a message about the importance of absolute truthfulness by corporate executives in dealing with their shareholders.

In the wake of the Enron debacle, in which numerous executives have been charged with issuing misleading statements about the company's prospects, the indictment of Ms. Stewart has signaled an expansion of the need for candor by executives -- even in personal financial matters -- if investors might care.