Prosecutors wield more power than any other actors in the criminal justice system. They have unreviewable power to go forward with a case or dismiss charges, to cut a deal with a defendant for a guilty plea or stand pat, and to recommend a severe sentence or plead for leniency. Unchecked power is always subject to abuse, and prosecutors sometimes engage in misconduct. Prosecutorial misconduct weakens the public's perception of the integrity of the legal system and undermines the ability of the courts to achieve justice.
Politically motivated prosecutions
Given the breadth of criminal law, prosecutors can find reason to prosecute just about anybody if they have the time, the money, and the motive. Critics of independent counsel Kenneth Starr's prosecution of President Clinton allege that Starr's primary motive for prosecution related to matters other than Clinton's alleged perjury. Anthony Lewis, a columnist for the New York Times, calls Starr's prosecution of Clinton “politics dressed as law.” Lewis claims no other prosecutor in the United States would have gone forward with a prosecution of a citizen for false testimony about sex in a civil case. In Lewis's opinion, few citizens have led such unblemished lives as to prevent a determined prosecutor from finding some basis for an indictment or information.
Suppressing evidence favorable to the defendant
Sometimes prosecutors, in their zeal to obtain a conviction, fail to turn over factual evidence that is favorable to the defendant when the evidence is material to guilt or punishment. One of the greatest threats to rational and fair fact‐finding in criminal cases comes from a prosecutor's hiding evidence that might prove a defendant's innocence. Between 1963, when the U.S. Supreme Court ruled in Brady v. Maryland that such a practice is a deprivation of due process, and 1999, at least 381 defendants nationally had a homicide conviction thrown out because prosecutors concealed evidence. Of the 381 defendants, 67 had been sentenced to death. The consequences of such misconduct when it is discovered can be serious. Convictions are reversed, cases are retried, appeals are brought that cost taxpayers millions of dollars, and public confidence in prosecutors is undermined.
When prosecutors knowingly allow the use of perjured testimony, a defendant's right to a fair trial is violated. The Supreme Court first established this rule in Mooney v. Holoban (1935), in which the Court said that the deliberate use of perjured testimony by the prosecutor and the deliberate nondisclosure of evidence that would have impeached such perjury violated the defendant's right to a fair trial. Ethically, a lawyer can't call a witness who he or she knows is going to lie. To do so is called suborning perjury. Critics of former Los Angeles district attorney Marcia Clark claim that she knew that police officer Mark Fuhrman (who said he had found a bloody glove behind O.J. Simpson's residence) was going to lie on the witness stand about not having used the “N” word. Clark's decision to call Fuhrman to testify may have lost the Simpson case because it opened the door for Simpson's defense team to expose Furhrman's perjury to the jury, thereby raising reasonable doubts in the jurors' minds about the credibility of the testimony of police officers in this case.
Controlling prosecutorial misconduct
Sanctions for prosecutorial misconduct include appellate reversal of convictions, finding the prosecutor in contempt of court, referring the prosecutor to a bar association grievance committee, and removing the prosecutor from office.
In the view of legal analyst Bennett Gershman, prosecutorial misconduct persists because of the unavailability or inadequacy of penalties visited upon the prosecutor personally in the event of unethical behavior. Although an appellate court can punish a prosecutor by telling him or her not to act in the same way again or by reversing a conviction, such sanctions don't hold the prosecutor personally accountable. During the course of a trial, the prosecutor is absolutely immune from any civil liability that might arise due to his or her official conduct. Moreover, appellate courts can affirm a conviction despite the presence of serious prosecutorial misconduct by merely invoking the harmless error doctrine. Under this doctrine, an appellate court determines that errors were of such a minor or trivial nature that they didn't harm the defendant's rights.