Faced with a growing legal and public-relations crisis spinning out of control, Morgan Stanley Dean Witter made a strategic decision last month to call in lawyers from Paul, Weiss, Rifkind, Wharton & Garrison to investigate a payment made by the investment bank to a police informant in a matter involving a former employee.

Though Morgan Stanley faced a unique set of circumstances, its decision to call in Paul Weiss rather than rely on its primary outside counsel to conduct an independent, internal investigation, is becoming more common in corporate boardrooms across the country.