READ MOREPeter Zeidenberg, who served as the assistant special counsel in the investigation of former White House aide Scooter Libby, argued in the Washington Post that appointing one would be a mistake."Prosecutors are not journalists, and their job is not to inform the public of the results of their investigations," Zeidenberg wrote. "Rather, their mission is to gather all of the relevant facts and determine whether a crime was committed and, if so, whether it can be proved in court beyond a reasonable doubt. Their work, when done properly, is done in secret."That means that if critical evidence was found in the case but it was in, say, Russia and therefore unobtainable, "then it would be improper to seek an indictment. Critically, the entire investigation would then remain secret. It would be a violation of law for a prosecutor to make public the results of a grand jury investigation that did not result in an indictment."So a special counsel could find incriminating information and keep it secret forever. Alternatively, a special counsel, in an effort to justify its efforts and expenditures, would have a tremendous incentive to get a prosecution even if it's unnecessary or unwarranted.