In the American legal system, prosecutors hold significant power. They decide who to charge, what crimes to charge them with, and when to drop a case. This power, known as prosecutorial discretion, isn't unlimited. In South Dakota, the guiding principle is that a prosecutor's primary duty is to seek justice, not simply to rack up convictions.

This core idea is formalized in the South Dakota Rules of Professional Conduct. Specifically, Rule 3.8 outlines the "Special Responsibilities of a Prosecutor." It mandates that they must refrain from prosecuting a charge that they know is not supported by probable cause. This ethical obligation is the foundation upon which all other legal constraints are built, ensuring that the power to prosecute is wielded fairly.

The most fundamental check on a prosecutor's power to charge someone with a crime is found in state law. South Dakota Codified Laws (SDCL) Title 23A governs criminal procedure and sets the floor for initiating a case. The central requirement is the existence of probable cause—a standard that must be met before a criminal complaint, information, or indictment can be filed.

This means a prosecutor can't just proceed with a case on a whim or a weak tip. They must review the evidence gathered by law enforcement—witness statements, physical evidence, reports—and make a professional judgment. Is there enough credible information to lead an ordinary, prudent person to believe the suspect is guilty? If not, the case cannot ethically or legally move forward.

Beyond state statutes and ethical rules, the U.S. and South Dakota Constitutions provide powerful protections against prosecutorial overreach. Two key doctrines are vindictive prosecution and selective prosecution. While difficult to prove, they serve as crucial boundaries on a prosecutor's discretion.

Vindictive prosecution occurs when a prosecutor retaliates against a defendant for exercising a legal right. For example, if a defendant successfully appeals a conviction, a prosecutor cannot then recharge them with a more serious crime out of spite for having to go through a new trial. The courts presume vindictiveness in such scenarios, and the burden falls on the prosecution to prove their decision was based on new evidence or other legitimate reasons.

Selective prosecution is the claim that a defendant was targeted for prosecution based on an unjustifiable standard, such as their race, religion, or political beliefs. To succeed with this defense, a defendant must show two things: that the prosecutor's policy had a discriminatory effect, and that it was motivated by a discriminatory purpose. This is a very high bar, as established in cases like State v. Gehrke (1992), where the South Dakota Supreme Court affirmed the difficulty of proving that others in similar situations were not prosecuted.

Finally, prosecutors have a duty to act as neutral ministers of justice. Their goal is not personal victory or political gain. This means they must set aside personal feelings about a suspect, the nature of the crime, or public opinion when making charging decisions.

This requirement of neutrality forces prosecutors to act as gatekeepers for the justice system. They must evaluate cases based on the facts and the law, and nothing else. If the evidence is weak, or if they believe the suspect is innocent despite what a police report might say, their duty is to decline prosecution. This role is essential for protecting the innocent and maintaining the integrity of the courts.

This quote illustrates discretion in action. Deciding to offer a diversion program instead of pursuing a conviction is a perfect example of a prosecutor seeking a just outcome, rather than just a win, based on the specific circumstances of a case.

Ready to check your understanding of these critical limits?

The boundaries placed on prosecutorial discretion—from ethical rules and statutory standards to constitutional protections—are designed to ensure that the immense power to charge an individual with a crime is exercised with fairness, neutrality, and a commitment to justice.