A prosecutor is a government lawyer who brings and pursues criminal cases on behalf of the public. The prosecutor definition most people are looking for comes down to this: rather than representing an individual victim, a prosecutor represents the state or federal government, decides which cases become criminal charges, and then carries those cases through the court system. They work in the executive branch at every level, from municipal courthouses handling noise complaints to federal courts handling fraud and national security matters.
What Prosecutors Actually Do
A prosecutor’s work starts long before trial. They review police reports, witness statements, and forensic results with law enforcement to decide whether an investigation has produced enough evidence to justify charges. If the answer is yes, they file formal charging documents. In felony cases, that is often an indictment returned by a grand jury or, in some jurisdictions, an information filed directly by the prosecutor’s office. The document lays out exactly what crimes the defendant is accused of committing.
Before trial, prosecutors manage the exchange of evidence with the defense, argue pretrial motions, and negotiate plea agreements. Most cases end in a plea rather than a trial. Under the Federal Rules of Criminal Procedure, a plea agreement can involve dropping certain charges, recommending a particular sentence, or agreeing that a specific sentencing range applies.1Legal Information Institute. Federal Rules of Criminal Procedure Rule 11
When a case does go to trial, the prosecutor calls witnesses, introduces evidence, cross-examines the defense’s witnesses, and delivers opening and closing arguments to persuade the jury of guilt.
The Duty to Seek Justice, Not Just Convictions
A prosecutor’s job is not simply to win. The Supreme Court said as much in 1935: a prosecutor represents a government “whose interest … in a criminal prosecution is not that it shall win a case, but that justice shall be done.”2Justia. Berger v United States, 295 US 78 That principle separates prosecutors from every other advocate in the courtroom.
The American Bar Association’s Model Rule 3.8 translates the principle into specific duties. Prosecutors cannot pursue charges they know lack probable cause. They must disclose evidence that could help the defense. They cannot seek waivers of important rights from defendants who do not have a lawyer. And when a prosecutor later learns of credible evidence that a convicted person may be innocent, the rule requires disclosure to the court and the defendant, plus further investigation.3American Bar Association. Rule 3.8 Special Responsibilities of a Prosecutor
Types of Prosecutors in the American Legal System
Prosecutors exist at every level of government, and each handles a different slice of criminal law.
Federal Prosecutors
The President appoints a United States Attorney for each of the 94 federal judicial districts, subject to Senate confirmation.4Office of the Law Revision Counsel. 28 USC 541 – United States Attorneys These prosecutors and their Assistant United States Attorneys handle federal crimes such as drug trafficking across state lines, fraud against the federal government, immigration offenses, and racketeering. Federal statute requires them to prosecute all offenses against the United States within their district and to handle civil matters involving the federal government.5Office of the Law Revision Counsel. 28 USC 547 – Duties They operate under policies set by the Department of Justice.
State and Local Prosecutors
District Attorneys, State’s Attorneys, or Commonwealth’s Attorneys handle most criminal cases in the country, from misdemeanors like petty theft to serious felonies including murder and armed robbery. The United States is unusual globally in that most local prosecutors are elected rather than appointed. These elected officials typically oversee offices staffed by assistant prosecutors who carry the day-to-day caseload.
City and Municipal Prosecutors
At the lowest level, city or municipal attorneys prosecute ordinance violations such as noise complaints, building code infractions, and minor traffic offenses. These cases generally end in fines rather than jail time, and the proceedings tend to be faster and less formal than felony prosecutions.
Prosecutorial Discretion
Few powers in the legal system are as broad as prosecutorial discretion. Prosecutors decide whether to file charges, what charges to bring, whether to offer a plea deal, and whether to drop a case entirely. The Supreme Court has repeatedly recognized that these decisions rest almost entirely within the prosecutor’s judgment, as long as probable cause exists. The charging decision often matters more than the trial itself.
Several factors guide these calls: the strength of the evidence, the seriousness of the offense, the defendant’s criminal history, the impact on the victim, and whether the public interest is served by prosecution. A prosecutor might decline to charge a first-time offender caught with a small amount of drugs, or might aggressively pursue a repeat violent offender even when the evidence is only moderate.
Discretion also extends to diversion. A pretrial diversion program routes certain defendants away from the normal court process; successful completion can lead to reduced charges or outright dismissal, and failure sends the defendant back into the standard prosecution pipeline.6United States Department of Justice. Justice Manual 9-22.000 – Pretrial Diversion Program Violent offenses and defendants with significant criminal histories are generally excluded.
The Burden of Proof
The prosecutor bears the full weight of proving guilt beyond a reasonable doubt. This is the highest standard of proof in American law. The defendant does not have to prove anything, testify, or present a single witness. The burden sits on the prosecution from start to finish.
Meeting the standard means proving every element of the charged crime. For most offenses, that includes both a physical act and a mental state. A theft charge, for example, requires proving that the defendant took someone else’s property and intended to permanently deprive the owner of it. If the prosecutor fails to prove even one element, the result is acquittal, and the defendant cannot be retried for the same offense.
Brady Obligations
One of the most important limits on prosecutors comes from the Supreme Court’s 1963 decision in Brady v. Maryland. The Court held that suppressing evidence favorable to the defendant violates due process when that evidence is material to guilt or punishment, regardless of whether the prosecutor acted in good faith or bad faith.7Library of Congress. Brady v Maryland, 373 US 83 Prosecutors must turn over any evidence that could help the defense, including evidence that undermines the credibility of a government witness.
If a Brady violation surfaces during trial, the court can declare a mistrial. When violations come to light after conviction, the most common result is that the conviction gets overturned. Brady violations remain one of the leading causes of wrongful convictions in the United States, partly because enforcement depends on discovering the violation at all.
Duties to Crime Victims
Federal prosecutors carry specific legal duties toward crime victims under the Crime Victims’ Rights Act. The statute requires Department of Justice employees involved in prosecutions to make their best efforts to see that victims receive the rights the law guarantees.8Office of the Law Revision Counsel. 18 USC 3771 – Crime Victims Rights Those rights include:
- the right to be reasonably protected from the accused
- the right to timely notice of court proceedings, parole hearings, and any release or escape of the accused
- the right to attend public court proceedings and to be heard during proceedings involving release, plea agreements, and sentencing
- the right to confer with the prosecutor handling the case
- the right to full and timely restitution as provided by law
- the right to be told about any plea bargain or deferred prosecution agreement in a timely manner
Prosecutors must also advise victims that they can seek their own attorney’s advice regarding these rights.8Office of the Law Revision Counsel. 18 USC 3771 – Crime Victims Rights Many state systems have parallel victim-rights statutes, though the specifics vary.
Immunity and Accountability
Prosecutors enjoy absolute immunity from civil lawsuits for actions they take as courtroom advocates. The Supreme Court established that protection in Imbler v. Pachtman in 1976, reasoning that prosecutors need independence to make hard decisions without personal financial liability every time a case does not go well. The immunity covers decisions such as which charges to bring, what evidence to present at trial, and how to argue a case before a jury.
The protection is not unlimited. It applies only when a prosecutor functions as a legal advocate. When prosecutors act as investigators or administrators, they receive only qualified immunity, which can be overcome by showing they violated a clearly established constitutional right. In practice, suing a prosecutor personally for wrongful prosecution is extremely difficult, even in cases involving serious misconduct.
When prosecutors cross ethical lines, accountability comes mostly through professional discipline. State bar associations can impose sanctions ranging from reprimands to suspension to disbarment, though studies have consistently shown that serious discipline for prosecutors is rare. Federal prosecutors face internal review by the Department of Justice’s Office of Professional Responsibility, which can recommend sanctions from written reprimands to removal. The most common real-world consequence of misconduct is damage to the case itself, as convictions get overturned on appeal when courts find that misconduct denied the defendant a fair trial.