In court, a prosecutor represents the government through every stage of a criminal case: filing charges, arguing pre-trial motions, negotiating plea deals, picking jurors, presenting witnesses and evidence at trial, cross-examining the defense, delivering closing arguments, and recommending a sentence after conviction. What a prosecutor does in court is shaped by one overriding obligation that sits above all the tactical work: the duty to seek justice, not simply to win. Because roughly 90 to 95 percent of criminal cases end in plea bargains, most of that courtroom work happens at hearings, not trials.
The Duty That Shapes Everything Else
Every courtroom task a prosecutor performs rests on a single principle the U.S. Supreme Court laid out in 1935: the government’s interest in a criminal case “is not that it shall win a case, but that justice shall be done.”1Library of Congress. Berger v. United States, 295 U.S. 78 (1935) A prosecutor can advocate hard, but cannot use improper methods to secure a conviction.
Professional conduct rules in nearly every state put real limits on how the job gets done. A prosecutor cannot file charges without probable cause, cannot try to obtain waivers of important rights from a defendant who has no lawyer, and must turn over evidence that helps the defense. Violations can lead to case dismissal, overturned convictions, or discipline against the lawyer personally.
Filing Charges and the Grand Jury
Before anything reaches a trial courtroom, a prosecutor has to decide whether charges are warranted. For serious federal crimes and in many states, that decision goes through a grand jury. The prosecutor presents evidence to a panel of citizens who then vote on whether probable cause exists to issue an indictment. The defendant generally has no right to appear, present evidence, or have a lawyer in the grand jury room.
That gives the prosecutor substantial control. The grand jury relies on the prosecutor to explain the law, present witnesses, and run the proceeding. Most states require prosecutors who hold strong evidence of innocence to share it with the grand jury; federal prosecutors are not bound by that rule, on the theory that the defendant will get a full chance to present exculpatory evidence at trial.
Not every case goes through a grand jury. In many state systems, prosecutors file charges directly through a document called an information, which typically follows a preliminary hearing where a judge independently decides whether probable cause exists.
Handing Over Evidence to the Defense
One of the heaviest obligations a prosecutor carries runs throughout the case: disclosing evidence favorable to the defendant. The Supreme Court held in 1963 that withholding evidence material to guilt or punishment violates due process, regardless of whether the prosecutor acted in bad faith.2United States Department of Justice. Policy Regarding Disclosure of Exculpatory and Impeachment Information
The duty reaches beyond evidence of outright innocence. Prosecutors must also disclose material that could be used to undermine a government witness, such as a cooperating witness’s plea deal, prior inconsistent statements, or a law enforcement officer’s history of dishonesty. Department of Justice policy tells federal prosecutors to take a broad view and err on the side of disclosure, whether or not the defense asks. If new favorable evidence surfaces mid-trial, it has to be turned over promptly.2United States Department of Justice. Policy Regarding Disclosure of Exculpatory and Impeachment Information
Separately, federal rules require prosecutors to turn over a broad range of case materials once the defense asks: the defendant’s own recorded statements, prior criminal history, documents and physical items the government intends to use at trial, and results of any tests or examinations. For expert witnesses, the prosecutor must provide written summaries of the expert’s expected opinions, the reasoning behind them, and the expert’s qualifications, far enough before trial for the defense to respond.3Legal Information Institute. Federal Rules of Criminal Procedure Rule 16 – Discovery and Inspection Internal work product like strategy memos stays protected, but courts watch that line closely.
Early Court Appearances
Courtroom work starts at the arraignment, where the defendant hears the formal charges and enters a plea. The prosecutor presents the charges and gives the court a factual summary supporting them.
Bail hearings usually follow soon after. The prosecutor may argue for pre-trial detention based on flight risk, danger to the community, or the seriousness of the offense, or may agree to release with conditions like electronic monitoring or no-contact orders. The judge decides, but the prosecutor’s position carries weight.
Pre-trial motions take up a large share of courtroom time. Defense attorneys often move to suppress evidence, arguing police obtained it through an illegal search or a coerced confession. The prosecutor defends how the evidence was collected, usually by calling the officers involved and showing the constitutional requirements were met.4National Institute of Justice. Law 101 – Legal Guide for the Forensic Expert – Motion to Suppress Losing a suppression motion can collapse a case, so these hearings often matter more than any later proceeding.
Negotiating and Presenting Plea Deals
Because the overwhelming majority of criminal cases never reach trial, plea bargaining is the duty a prosecutor exercises most often. A plea agreement is a negotiated resolution in which the defendant pleads guilty, usually to a reduced charge or in exchange for a sentencing recommendation, rather than going to trial.
Federal rules allow a prosecutor to offer three kinds of concessions: dropping other charges, recommending a particular sentence that the judge can accept or reject, or agreeing to a specific sentence that binds the court once the deal is accepted.5Legal Information Institute. Federal Rules of Criminal Procedure Rule 11 – Pleas Judges are excluded from the negotiations, but they review the result.
Once a defendant enters the guilty plea, the prosecutor participates in the plea colloquy, the in-court exchange where the judge confirms the plea is knowing and voluntary. The court must find a factual basis, and it can satisfy that by questioning the prosecutor about the evidence. The agreement is disclosed in open court. If the judge rejects it, the defendant can withdraw the plea.5Legal Information Institute. Federal Rules of Criminal Procedure Rule 11 – Pleas
Picking the Jury
When a case does reach trial, the first in-court task is jury selection through a process called voir dire. The prosecutor and defense attorney question potential jurors, probing for bias or experience that would prevent fair evaluation of the evidence. A prosecutor might ask about personal ties to law enforcement, prior experience in the criminal justice system, or media exposure to the case.
Each side can remove jurors two ways. Challenges for cause require the lawyer to argue a specific juror cannot be impartial and the judge to agree; those are not numerically limited. Peremptory challenges allow removal without a stated reason, but the number is capped. In federal cases, the government gets 20 peremptory challenges in capital cases, 6 in other felony cases, and 3 in misdemeanor cases.6Legal Information Institute. Federal Rules of Criminal Procedure Rule 24 – Trial Jurors
Peremptory strikes carry one major limit: a prosecutor cannot use them to remove jurors based on race. If the defense alleges racial discrimination, the burden shifts to the prosecutor to give a race-neutral reason, and the judge decides whether the explanation is genuine or a pretext. The rule has since expanded to cover gender and other characteristics.7United States Courts. Facts and Case Summary – Batson v. Kentucky
Presenting the Government’s Case
Trial opens with the prosecutor’s opening statement, a preview of what the evidence will show. The opening is not evidence itself, just a roadmap. The prosecutor goes first because the government carries the burden of proof.
Calling Witnesses
Direct examination is where the case actually gets built. Police officers walk through their investigation, victims describe what happened, and forensic analysts explain lab results. On direct, questions are open-ended (“What did you see?” rather than “You saw the defendant, didn’t you?”) so witnesses testify in their own words.
Expert witnesses add an extra step. Before an expert can offer opinions, the prosecutor has to establish that the witness is qualified and that the methodology is reliable. The defense gets a chance to challenge credentials or methods before any opinion reaches the jury.
Admitting Physical Evidence
The prosecutor is also responsible for getting physical items into evidence, from surveillance footage to financial records to a weapon. Each item has to be authenticated: a witness has to identify what it is and how it ties to the case. A detective may identify a firearm by its serial number; a forensic technician may walk the court through the chain of custody for a DNA sample. If the foundation is not properly laid, the judge keeps the item out. Once the witnesses have testified and the exhibits are in, the prosecutor rests.
Responding to the Defense
After the prosecution rests, the defense presents its case, and the prosecutor shifts to testing it. Cross-examination is the main tool. Unlike direct, cross relies on leading questions that control the witness’s answers and expose inconsistencies with earlier statements, bias, memory gaps, or other reasons to doubt credibility.8Legal Information Institute. Federal Rules of Evidence Rule 611 – Mode and Order of Examining Witnesses and Presenting Evidence
Throughout the defense presentation, the prosecutor also watches for inadmissible evidence and objects when the rules are broken. Hearsay, an out-of-court statement offered to prove the truth of what it asserts, is one of the most common objection grounds.9Legal Information Institute. Federal Rules of Evidence Rule 801 – Definitions That Apply to This Article; Exclusions from Hearsay A timely objection keeps the jury from hearing excluded material; failing to object can waive the issue on appeal.
Once the defense rests, the prosecutor may put on rebuttal evidence that specifically answers claims the defense raised. Rebuttal is narrow. It cannot repeat the main case or introduce proof that should have come in earlier. The point is to answer new factual claims, such as an alibi.
Closing Arguments
Closing argument is the prosecutor’s last direct conversation with the jury. The opening previewed the evidence; the closing connects it. The prosecutor walks through testimony and exhibits, tying each piece to the legal elements the government had to prove and explaining why the evidence eliminates reasonable doubt.
The prosecutor also addresses weaknesses in the defense’s case: contradicted testimony, a theory that does not match the facts, witnesses who lacked credibility. After the defense’s closing, the prosecutor typically delivers a short rebuttal argument. That final word is a structural advantage, and it exists because the government carries the burden of proof.
Sentencing, Restitution, and Victims
A conviction or guilty plea does not end a prosecutor’s work in court. At sentencing, the prosecutor recommends a punishment. Federal policy directs prosecutors to seek a sentence that reflects the seriousness of the offense, deters future crime, protects the public, and provides for restitution to victims.10United States Department of Justice. JM 9-27.000 – Principles of Federal Prosecution
Before the hearing, a probation officer prepares a pre-sentence investigation report covering the defendant’s background, criminal history, and the circumstances of the offense. The prosecutor receives a copy at least ten days before sentencing and can supplement or correct it if it contains errors or omissions.11Office of the Law Revision Counsel. 18 U.S. Code 3552 – Presentence Reports
Restitution
For many federal offenses, restitution is mandatory. The court must order the defendant to compensate victims for property damage, medical expenses, lost income, and other direct losses from the crime.12Office of the Law Revision Counsel. 18 U.S. Code 3663A – Mandatory Restitution to Victims of Certain Crimes The prosecutor presents the evidence supporting the amount, which usually means working with victims ahead of time to document losses. If the defendant disputes the figure, the judge holds a separate hearing.
The Victim’s Role
Federal law gives crime victims the right to be reasonably heard at sentencing, to confer with the prosecutor on their case, and to receive timely notice of plea bargains and court proceedings.13Office of the Law Revision Counsel. 18 U.S. Code 3771 – Crime Victims Rights The prosecutor is the primary point of contact for victims throughout the case. At sentencing, the prosecutor may present victim impact statements or arrange for the victim to address the court directly, while balancing those interests against the broader duty to seek a just outcome rather than the harshest one available.