Getting to the bottom of governmental wrongdoing is something of a cottage industry in Washington nowadays. No fewer than four independent counsel -- formerly known as special prosecutors -- are conducting probes of alleged misdeeds by current and former Administration officials, most notably the Iranscam investigation led by Lawrence E. Walsh. But last week a pair of challenges cast doubt on the legal validity of those efforts.
The first came from Lieut. Colonel Oliver North, whose attorneys filed suit in U.S. District Court to stop Walsh's probe. Their argument: the broad mandate given to the court-appointed special prosecutor is a violation...