A prosecution is the formal legal process in which the government files criminal charges against a person and then presents evidence in court to prove those charges. The prosecution definition most people need comes down to this: it is the government’s pursuit of a criminal case, from the first charging document through the verdict or dismissal. A government attorney — not the victim, not the police — decides whether that pursuit happens, what charges to bring, and when to stop.
Prosecution Is Not the Same as Arrest or Investigation
An arrest puts you in custody. An investigation gathers facts. Neither one is a prosecution. Prosecution begins only when the government files official charges with a court and starts the legal machinery aimed at a conviction. A police arrest does not guarantee that charges will follow. The prosecutor independently evaluates the evidence first.
The term also reaches beyond criminal law. Government agencies bring civil and administrative enforcement actions — regulatory fines, license revocations, environmental penalties — and those are sometimes called prosecutions too. The structure is similar: formal charges, evidence, adjudication. The stakes and the burden of proof are lower. Most people encounter the word in its criminal sense, and that is the meaning that carries the constitutional weight.
How a Prosecution Begins
A criminal prosecution starts with one of three charging documents:
- A complaint is a sworn statement by a law enforcement officer or prosecutor laying out the facts and the alleged crimes. Complaints are often used for initial charges and arrests because they can be prepared quickly.
- An information is a formal charging document filed directly by the prosecutor without a grand jury. A judge reviews it and determines whether probable cause exists to proceed.
- An indictment is a formal charge issued by a grand jury after reviewing evidence from the prosecutor. The Fifth Amendment requires a grand jury indictment for all federal felony prosecutions: “no person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury.”1Constitution Annotated. Amdt5.2.2 Grand Jury Clause Doctrine and Practice
The grand jury requirement applies only in federal court. It has not been extended to the states through the Fourteenth Amendment, and many states let prosecutors proceed by information for most offenses.1Constitution Annotated. Amdt5.2.2 Grand Jury Clause Doctrine and Practice
Once charges are filed, the case moves through an initial court appearance, possible bail hearings, discovery where both sides exchange evidence, pre-trial motions, and eventually a trial or a plea agreement.2United States Department of Justice. Steps in the Federal Criminal Process
Who Prosecutes Criminal Cases
At the state level, elected District Attorneys handle criminal cases for their communities. They decide which cases to charge, what charges to bring, and whether to offer plea agreements. In larger offices, assistant district attorneys handle most of the day-to-day courtroom work.
At the federal level, United States Attorneys serve as the chief federal law enforcement officers in each of the 94 federal judicial districts. The President appoints them, and the Senate confirms them.3Offices of the United States Attorneys. About the U.S. Attorneys’ Offices Their statutory duties include prosecuting federal crimes, representing the government in civil matters, and collecting certain debts owed to the federal government.4Office of the Law Revision Counsel. 28 USC 547 – Duties All U.S. Attorney offices operate under the Attorney General.
When a case is captioned, the prosecuting side is labeled “the State,” “the People,” or “the United States.” That naming reflects a core idea: a crime is treated as an offense against the whole community, not just the individual victim. The prosecutor represents the public.
Prosecutorial Discretion and Its Limits
Prosecutors have broad authority to decide whether to bring charges, which charges to file, and whether to negotiate a plea. This power — prosecutorial discretion — is one of the most consequential decision points in the criminal justice system.
Federal prosecutors follow guidelines in the Department of Justice’s Justice Manual. Those guidelines direct prosecutors to bring charges when the evidence will likely lead to a conviction, unless the prosecution would serve no substantial federal interest, the person faces effective prosecution in another jurisdiction, or an adequate non-criminal alternative exists. Prosecutors also weigh the seriousness of the offense, the person’s criminal history, and the deterrent effect of a prosecution.5Congressional Research Service. Federal Prosecutorial Discretion: A Brief Overview
Discretion has constitutional limits. Under the Equal Protection Clause, prosecutors cannot single out defendants based on race, religion, or other protected characteristics. To prove selective prosecution, a defendant must show the policy had a discriminatory effect and was motivated by discriminatory intent.6Justia Supreme Court. United States v Armstrong, 517 US 456 (1996)
Prosecutors can also drop charges after filing them. The step is called a nolle prosequi, meaning “not to wish to prosecute,” and it can happen at any point before a verdict — often because evidence turns out weaker than expected or a key witness becomes unavailable.
What the Government Must Prove
In a criminal prosecution, the government must prove every element of the charged offense beyond a reasonable doubt. The Supreme Court established this as a constitutional requirement in In re Winship, holding that due process protects the accused against conviction “except upon proof beyond a reasonable doubt of every fact necessary to constitute the crime with which he is charged.”7Legal Information Institute. In the Matter of Samuel Winship, Appellant
Beyond a reasonable doubt does not mean beyond all doubt. It means no reasonable alternative explanation exists on the evidence. The burden stays on the prosecution from start to finish. The defendant never has to prove innocence, and jury instructions that shift the burden or dilute the presumption of innocence violate due process.8Constitution Annotated. Amdt14.S1.5.5.5 Guilt Beyond a Reasonable Doubt
Civil and administrative enforcement actions use a lower standard: preponderance of the evidence, meaning the violation more likely than not occurred. That gap is why someone can be acquitted in criminal court yet still face consequences in a civil or administrative proceeding based on the same conduct.
Your Rights When You Are Being Prosecuted
The Sixth Amendment exists because of how much power a prosecution gives the government. Its protections apply to every criminal case, from a misdemeanor traffic offense to a capital charge:9Constitution Annotated. Sixth Amendment
- A speedy and public trial, without unnecessary delay and open to the public.
- An impartial jury drawn from the area where the crime allegedly occurred.
- Notice of the charges and the factual basis for them.
- The right to confront and cross-examine the witnesses testifying against you.
- Compulsory process — the power to subpoena witnesses to testify on your behalf.
- The right to counsel, with court-appointed representation if you cannot afford a lawyer.
These are structural limits on prosecutorial power. The government has vastly more resources than any individual defendant, and the consequences of a wrongful conviction are severe enough to justify real obstacles in the prosecution’s path.
How Prosecutions End
Most criminal cases never reach trial. Researchers estimate that roughly 90 to 95 percent of criminal cases in both federal and state courts are resolved through plea bargains.10Bureau of Justice Assistance. Plea and Charge Bargaining In a plea agreement, the defendant pleads guilty, often to a reduced charge, in exchange for a lighter sentence or dismissal of other counts.
Cases that go to trial end in either a conviction or an acquittal. An acquittal means the jury or judge found the evidence insufficient to prove guilt beyond a reasonable doubt. Under the Double Jeopardy Clause of the Fifth Amendment, the government generally cannot retry someone after an acquittal. That verdict is final.
Prosecutors can also dismiss charges before trial through a nolle prosequi filing or a motion to dismiss. Charges dropped this way do not necessarily prevent the government from refiling later, as long as the statute of limitations has not expired. Dismissal and acquittal can look similar from the outside, but only an acquittal permanently ends the prosecution.
Time Limits on Bringing a Prosecution
The government cannot prosecute whenever it feels like it. Statutes of limitations set firm deadlines for filing charges after an alleged crime. Under federal law, most non-capital offenses must be charged within five years.11Office of the Law Revision Counsel. 18 USC 3282 – Offenses Not Capital State time limits vary widely by offense. Serious crimes like murder typically have no limitation period; minor offenses may need to be charged within one to three years.
If the clock runs out before charges are filed, the prosecution is barred regardless of how strong the evidence is. It is one of the most absolute defenses in criminal law. The rationale is partly practical, since evidence degrades and witnesses forget, and partly about fairness: people should not have to live under the indefinite threat of prosecution.