A federal prosecutor, formally called an Assistant United States Attorney, represents the United States government in court. The work covers investigating and charging federal crimes, trying those cases or negotiating pleas, arguing at sentencing, defending convictions on appeal, handling civil lawsuits brought by or against the government, and collecting money owed to the United States.1Office of the Law Revision Counsel. 28 USC 547 – Duties Every one of those tasks sits under a single obligation the Supreme Court spelled out nearly a century ago: the job is to see that justice is done, not to win.
The Duty That Frames the Job
In 1935, the Supreme Court described a United States Attorney as “the representative not of an ordinary party to a controversy, but of a sovereignty whose obligation to govern impartially is as compelling as its obligation to govern at all.” The prosecutor “may strike hard blows,” the Court said, but “is not at liberty to strike foul ones,” and it is as much the prosecutor’s duty to prevent a wrongful conviction as to pursue a just one.2Justia Law. Berger v. United States, 295 U.S. 78 (1935)
That principle shapes concrete rules throughout the Justice Manual, from charging standards to the requirement that prosecutors hand over evidence that helps the defense. Falling short can mean overturned convictions, bar discipline, and lost cases.
Advising Investigators Before Charges Are Filed
Federal prosecutors do not conduct surveillance or make arrests. They do, however, work alongside agents from the FBI, DEA, ATF, and other agencies well before anyone is charged, serving as the legal check on how an investigation is built. Evidence obtained the wrong way can be thrown out at trial, so catching problems early matters.
A common task at this stage is reviewing search warrant applications. Federal rules require an affidavit showing probable cause before a magistrate judge will sign a warrant, and the prosecutor makes sure the paperwork meets that standard.3Legal Information Institute. Federal Rules of Criminal Procedure Rule 41 – Search and Seizure Prosecutors also draft grand jury subpoenas compelling witnesses to testify or produce documents, and they keep asking the same question as the investigation develops: is there enough here to charge, or does the case need more?
Deciding Whether to Charge
Charging someone with a serious federal crime is not a decision the prosecutor makes alone. The Fifth Amendment requires that federal felony charges come through a grand jury indictment.4Congress.gov. Fifth Amendment Grand Jury Clause Doctrine and Practice The prosecutor presents witnesses and documents to a panel of citizens meeting in secret, and the grand jurors vote on whether probable cause exists to believe a specific person committed a federal crime. If they vote yes, an indictment issues. If not, the case stops.5United States Department of Justice. Charging
Internal policy adds another filter. Under the Principles of Federal Prosecution, a prosecutor should move forward only if the admissible evidence will probably be sufficient to obtain and sustain a conviction and the prosecution serves a substantial federal interest. Even then, the prosecutor is supposed to consider whether a state court could handle the case effectively, or whether a civil or administrative response would do the job better.6United States Department of Justice. Justice Manual – 9-27.000 Principles of Federal Prosecution
Turning Over Evidence That Helps the Defense
This is where the duty-to-seek-justice principle has real teeth. Under Brady v. Maryland, suppressing evidence favorable to the accused violates due process whenever the evidence is material to guilt or punishment.7Justia Law. Brady v. Maryland, 373 U.S. 83 (1963) That includes information that could undermine a government witness: prior inconsistent statements, deals cut for testimony, criminal history.
Department of Justice policy goes beyond the constitutional floor. Prosecutors must disclose information “inconsistent with any element of any crime charged” or that “casts a substantial doubt upon the accuracy of any evidence” the government plans to use, and must do so whether or not the defense asks.8United States Department of Justice. Justice Manual – 9-5.000 Issues Related to Discovery, Trials, and Other Proceedings On top of that, the Federal Rules of Criminal Procedure give defendants the right to the government’s physical evidence, their own statements, their prior record as held by the government, scientific test results, and detailed information on any expert the prosecution plans to call.9Legal Information Institute. Federal Rules of Criminal Procedure Rule 16 – Discovery and Inspection
Blowing a disclosure obligation is one of the most serious mistakes a prosecutor can make. It can mean a reversed conviction, a mistrial, or personal discipline against the attorney.
Trying the Case or Negotiating a Plea
Most federal criminal cases never reach a jury. Roughly 97 to 98 percent of federal convictions come from plea agreements, where the defendant pleads guilty in exchange for dropped charges or a joint sentencing recommendation. Negotiating those deals is a core piece of the job.
For the small share of cases that go to trial, the prosecutor carries the burden of proving guilt beyond a reasonable doubt. That means opening and closing statements, direct examination of government witnesses, cross-examination of defense witnesses, and introducing physical evidence. Disclosure obligations keep running throughout the trial as new information surfaces.
Arguing at Sentencing
After a guilty verdict or plea, the prosecutor argues for a specific sentence. Federal judges start with the advisory Federal Sentencing Guidelines published by the United States Sentencing Commission. The prosecutor can push for upward adjustments the facts support, such as the aggravating-role enhancement when a defendant led a scheme involving others.10United States Sentencing Commission. Aggravating and Mitigating Role Adjustments Prosecutors also present victim impact evidence and argue for or against departures from the guideline range. The judge decides, but the prosecutor’s recommendation carries weight.
Looking Out for Victims
When a case has identifiable victims, federal law adds specific duties. The Crime Victims’ Rights Act gives victims the right to timely notice of proceedings, to attend them, to be heard at release and sentencing hearings, and to confer with the prosecutor. Department personnel must make “best efforts” to see those rights are honored.11Office of the Law Revision Counsel. 18 USC 3771 – Crime Victims’ Rights Victims also have to be told about any plea bargain or deferred prosecution agreement before it is finalized, so a case cannot be quietly resolved behind their backs.
Restitution is another prosecutor responsibility. For crimes of violence, property offenses, and fraud, the Mandatory Victims Restitution Act requires the court to order the defendant to compensate victims. The prosecutor consults with victims, provides the probation officer with a list of restitution amounts, and bears the burden of proving each victim’s loss.12GovInfo. 18 USC 3663A – Mandatory Restitution to Victims of Certain Crimes
Civil Work for the United States
A significant share of a federal prosecutor’s docket is not criminal at all. The work splits into two directions.
On defense, the prosecutor represents a federal agency or employee that has been sued. The claim might be personal injury at a federal facility or an employment discrimination suit against a department. The role is functionally that of any defense lawyer: assess the claim, build a strategy, argue the government’s position.
On offense, the prosecutor files suit for the United States. The most prominent example is the False Claims Act, which targets people and companies that knowingly submit false claims to the government. Healthcare and defense contracting fraud are frequent targets, and the statute lets the government recover three times its damages plus penalties.13U.S. Department of Justice. The False Claims Act Prosecutors also chase debts, fines, and penalties owed to the government, and handle civil forfeiture proceedings to seize property tied to criminal activity.14Office of the Law Revision Counsel. 18 USC 983 – General Rules for Civil Forfeiture Proceedings
Defending the Conviction on Appeal and After
If a defendant appeals, the prosecutor defends the conviction and sentence in the court of appeals. That means written briefs responding to the defendant’s arguments, and often oral argument before a panel of circuit judges.
Prosecutors also handle collateral attacks. The most common is a motion under 28 U.S.C. ยง 2255, which lets a federal prisoner argue that a sentence should be vacated for a constitutional violation, a jurisdictional defect, or a fundamental error. When the court cannot resolve the motion on the file alone, it notifies the U.S. Attorney’s office and sets a hearing, and the prosecutor responds.15Office of the Law Revision Counsel. 28 USC 2255 – Federal Custody; Remedies on Motion Attacking Sentence
The duty to seek justice does not stop at conviction either. When a prosecutor learns of new, credible evidence creating a reasonable likelihood that a convicted person did not commit the offense, professional conduct rules require prompt disclosure to the court and the defendant, along with further investigation.
Who Watches the Prosecutors
Federal prosecutors hold enormous discretion, and the Department of Justice runs an internal office to police how they use it. The Office of Professional Responsibility investigates allegations that Department attorneys have failed to meet professional standards in criminal prosecutions, civil litigation, and national security work. It reports to the Attorney General and takes complaints from judges, agencies, defense lawyers, private citizens, and prosecutors themselves.16Department of Justice. Office of Professional Responsibility Frequently Asked Questions
When OPR finds professional misconduct, it can refer the attorney to state bar disciplinary authorities. The office also monitors judicial opinions for findings of misconduct against Department lawyers, so a problem flagged by a judge is unlikely to stay buried.