Columnist David Weidner writes that it is time for the Securities and Exchange Commission to toughen up. While some argue that the SEC improved under Mary Schapiro's chairmanship, a couple of new developments could prove helpful, Weidner writes. Recently introduced legislation would strengthen the regulator's abilities to levy stiff penalties. "The second development is nomination of former federal prosecutor Mary Jo White as SEC chairman," Weidner writes. "The choice of Ms. White is a significant departure from a series of chairmen that have been political payoffs, lifelong bureaucrats or industry participants."