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Prosecutorial Discretion and Its Constitutional Limits


In 1992, several black men charged with federal crackcocaine offenses alleged in defense that they were selected for prosecution because of their race. They offered affidavits stating that, of twenty-four cases closed by a federal public defender's office in 1991, all of those charged with similar crack offenses had been black; that there are an equal number of white and nonminority crack users and dealers; and that whites are more likely to be prosecuted in more lenient state courts. The Supreme Court, in United States v. Armstrong (1996), held that these defendants were not entitled to access to the government's records to perfect their challenge to the prosecutor's discretion because they had not made a sufficient threshold showing that the prosecution acted on the basis of race.

The Court's decision in Armstrong illustrates the judiciary's general deference to the prosecutor's discretion. The prosecutor may choose which crimes and which persons to prosecute. She is entitled to prosecute whenever she has probable cause to believe a certain person committed a certain crime. She need not be certain that she can prove guilt beyond a reasonable doubt. In the twentieth century, there have always been many more legitimately prosecutable people than resources allow for prosecution, in addition to laws that the public has not wanted prosecutors to rigorously enforce.

In the United States, the exercise of these kinds of discretion is part of executive power, rather than legislative power or judicial power. Article II of the Constitution mandates the executive branch and its agents to "take Care that the Laws be faithfully executed.…" Prosecutorial discretion encompasses all aspects of a case; the prosecutor may decide whether to investigate, grant immunity, or allow a plea. Since the Constitution leaves these decisions in the hands of the executive, the policy of separation of powers weighs against too much judicial oversight of the prosecutor's discretion.

It would be difficult for judges to correct prosecutors even if there were no doctrine of separation of powers. To know whether a prosecutor has appropriately levied a charge, a judge would have to know about the prosecutor's entire docket of similar kinds of cases. This would consume more time than most courts have. Besides, there is no good reason to believe a judge would be more competent than the prosecutor to decide whether the seriousness of the crime and the weight of the evidence justifies going forward with the case. If the judge errs, she will not be subject to the judgment of the voters. If the judiciary must pause to consider the wisdom of a prosecution, even valued prosecutions that should go forth will be delayed. Under the Anglo-American system, the judge can only control the prosecutor by dismissing a case but cannot require her to go forward. Finally, a prosecutor whose discretion will be second-guessed may refuse to exercise discretion at all by routinely filing charges on everything she sees and letting the judges go to the effort of sorting it out. For these reasons courts leave the prosecutorial decision in the hands of the prosecutors and presume that discretion has been properly exercised.

Despite this broad rule, the Constitution does not confer unfettered discretion. Under the equal protection clause, courts may review a prosecutor's decision for unconstitutional motive such as race or religion. To succeed in a defense of selective prosecution, the accused must prove that prosecutorial policy had both a discriminatory effect and purpose. The Court first recognized this defense in yick wo v. hopkins (1886), where a Chinese laundryman in San Francisco had been prosecuted for violating a city laundry ordinance because of his race. The Court held that "though the law be fair on its face and impartial in appearance" when "applied with an evil eye and an unequal hand" it violated the defendant's constitutional right to equal protection.

Historically, the defense of selective prosecution has rarely succeeded. To prove it is expensive. The accused must examine walls of court files to show a pattern of racial discrimination. One way to transfer some (but not all) of these costs would be to require the prosecutor to gather her own files of all the relevant cases and turn them over to the defendant for examination. In Armstrong, the Court held that before the defendants could look at the government's files, they must provide "clear evidence" that the government failed to prosecute other similarly situated white defendants.

Critics of Armstrong argue that it renders selective prosecution largely impotent as a defense; they argue that Armstrong 's increased hostility toward statistical evidence and the defense's increased evidentiary burden immunize prosecutors from constitutional scrutiny. Although this criticism may be true, it does not mean that Armstrong is improvident. The judiciary accepts as a maxim that one should not prosecute red-haired people because they are red-haired. Yet, absent a rigorous standard of proof, selective prosecution is easy for a defendant to assert and hard for a prosecutor to disprove. Even a good faith but wrongful assertion imposes costs on the government and the defendant and delays decision on the truth of the charge. Moreover, the accused says only that the prosecutor was wrong because she chose to prosecute based on an unconstitutional motive like race or creed. To claim selective prosecution is not to claim innocence: the red-haired thief hasn't claimed he didn't steal, and the Zoroastrian murderer hasn't claimed that he didn't murder.

There are two more subtle yet important reasons why Armstrong 's heightened burden in proving selective prosection may make sense. First, when a court rules on a selective prosecution claim it must judge the validity of the prosecutor's defense: Had the defendants in Armstrong proffered clear evidence that white individuals were not similarly prosecuted, the Court would have had to evaluate whether Jamaican, Haitian, and black street gangs really did predominate crack distribution as the U.S. Attorney's office claimed. Today's judiciary is generally reluctant to involve itself in these complex and politically charged judgments and leaves it to the legislative branch to deal with them. Second, successful use of a selective prosecution defense was extremely rare even before Armstrong raised the bar. Most judges do not see a prosecutor's abuse of her discretion as a real problem, and little evidence supports a contrary conclusion. After all, in Armstrong it was Congress, not prosecutors, that imposed stiff mandatory sentencing guidelines on crack-cocaine dealers creating the disparity between powdered cocaine and crack-cocaine offenses.

James B. Zagel


Heller, Robert 1998 Selective Prosecution and Federalization of Criminal Law: The Need for Meaningful Judicial Review of Prosecutorial Discretion. University of Pennsylvania Law Review 145:1309–1358.

Jampol, Melissa L. 1997 Goodbye to the Defense of Selective Prosecution. Journal of Criminal Law and Criminology 87: 932–966.

Love, Marci A. 1997 United States v. Armstrong: The Supreme Court Formulates a Discovery Standard for Selective Prosecution. Temple Political Civil Rights Law Review 7:191–219.

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