A prosecutor is a legal representative of the prosecution in countries with either the common law adversarial system, or the civil law inquisitorial system. The prosecution is the legal party responsible for presenting the case in a criminal trial against an individual accused of breaking the law. Typically, the prosecutor represents the government in the case brought against the accused person.

Prosecutors are typically lawyers who possess a law degree, and are recognized as legal professionals by the court in which they intend to represent society (that is, they have been admitted to the bar).

They usually only become involved in a criminal case once a suspect has been identified and charges need to be filed. They are typically employed by an office of the government, with safeguards in place to ensure such an office can successfully pursue the prosecution of government officials. Often, multiple offices exist in a single country, especially in those countries with federal governments where sovereignty has been bifurcated or devolved in some way.

Since prosecutors are backed by the power of the state, they are usually subject to special professional responsibility rules in addition to those binding all lawyers. For example, in the United States, Rule 3.8 of the ABA Model Rules of Professional Conduct requires prosecutors to "make timely disclosure to the defense of all evidence or information that tends to negate the guilt of the accused or mitigates the offense." Not all U.S. states adopt the model rules; however, U.S. Supreme Court cases and other appellate cases have ruled that such disclosure is required. Typical sources of ethical requirements imposed on prosecutors come from appellate court opinions, state or federal court rules, and state or federal statutes (codified laws).

In Australia, Canada, England and Wales, Hong Kong, Northern Ireland, Republic of Ireland, Trinidad & Tobago, Guyana, Kenya, and South Africa, the head of the prosecuting authority is typically known as the Director of Public Prosecutions, and is appointed, not elected. A DPP may be subject to varying degrees of control by the Attorney General, usually by a formal written directive which must be published.

In Australia, the Offices of the Director of Public Prosecutions institute prosecutions for indictable offences on behalf of the Crown.^[1] At least in the case of very serious matters, the DPP will be asked by the police, during the course of the investigation, to advise them on sufficiency of evidence, and may well be asked, if he or she thinks it proper, to prepare an application to the relevant court for search, listening device or telecommunications interception warrants.

More recent constitutions, such as South Africa's, tend to guarantee the independence and impartiality of the DPP.

Prosecutors in Australia come in a few distinct species. Prosecutors of minor criminal cases in lower courts, are usually Police Sergeants with a traineeship in prosecution and advocacy lasting appoximately 1 year in duration, although they may hold law degrees. Crown Prosecutors are always lawyers, and typically barristers, and they represent the State or Commonwealth in serious criminal cases in higher courts, County Court and above. Aside from Police prosecutors and Crown prosecutors, government agencies usually have the authority to appoint non-lawyers to prosecute on their behalf, such as the RSPCA Inspectors.^[2]

In Canada, public prosecutors in most provinces are called Crown Attorney or Crown Counsel. They are generally appointed by the provincial Attorney-General.

Though Scots law is a mixed system, its civil law jurisdiction indicates its civil law heritage. Here, all prosecutions are carried out by Procurators Fiscal and Advocates Depute on behalf of the Lord Advocate, and, in theory, they can direct investigations by the police. In very serious cases, a Procurator Fiscal, Advocate Depute or even the Lord Advocate, may take charge of a police investigation. It is at the discretion of the Procurator Fiscal, Advocate Depute, or Lord Advocate to take a prosecution to court, and to decide on whether or not to prosecute it under solemn procedure or summary procedure. Other remedies are open to a prosecutor in Scotland, including fiscal fines and non-court based interventions, such as rehabilitation and social work. All prosecutions are handled within the Crown Office and Procurator Fiscal Service. Procurators fiscal will usually refer cases involving minors to Children's Hearings, which are not courts of law, but a panel of lay members empowered to act in the interests of the child.

In the United States, the director of a prosecution office may be known by any of several names depending on the jurisdiction, most commonly District Attorney. In Commonwealth states, like Virginia, they are known as Commonwealth's Attorney.

The prosecution is the legal party responsible for presenting the case against an individual or a corporation suspected of breaking the law, initiating and directing further criminal investigations, guiding and recommending the sentencing of offenders, and are the only attorneys allowed to participate in grand jury proceedings.^[3]

The titles of prosecutors in state courts vary from state to state and level of government (i.e. city, county, and state) and include the terms District Attorney in New York, California, Texas, Pennsylvania, Delaware, Massachusetts, North Carolina, Georgia, Nevada, Wisconsin, Oregon, and Oklahoma^[4]; City Attorney in California cities (typically prosecute only minor and misdemeanor offenses) Commonwealth's Attorney in Kentucky and Virginia; County Attorney in Nebraska^[5], Minnesota, and Arizona^[6]; County Prosecutor in New Jersey,^[7] Ohio, and Indiana^[8]; District Attorney General in Tennessee; Prosecuting Attorney in Arkansas,^[9] Hawaii, Idaho, Michigan, Washington, and West Virginia (as well as in Missouri where cities additionally use "City Attorneys" to prosecute on their behalf); State's Attorney in Connecticut, Florida, Illinois, Maryland, North Dakota, and Vermont; State Prosecutor; Attorney General in Delaware and Rhode Island; and Solicitor in South Carolina.^[10] Prosecutors are most often chosen through local elections, and typically hire other attorneys as deputies or assistants to conduct most of the actual work of the office. United States Attorneys are appointed by the President and confirmed by the Senate. They represent the federal government in federal court in both civil and criminal cases. Private attorneys general can bring criminal cases on behalf of private parties in some states.

Prosecutors are required by state and federal laws to follow certain rules. For example, the government must disclose exculpatory evidence to the defense;^[11] must disclose matters affecting the credibility of prosecution witnesses, such as an agreement to dismiss the witness's own charges in exchange for her testimony;^[12] must not destroy potentially useful evidence in bad faith;^[13] and must not use false testimony to secure a conviction.^[14] Failure to follow these rules may result in a finding of prosecutorial misconduct, although a 2013 investigation found that actual discipline for prosecutorial misconduct was lacking.^[15]

Prosecutors are also tasked with seeking justice in their prosecutions. "The United States Attorney," explained the U.S. Supreme Court,

Prosecutors in some jurisdictions have the discretion to not pursue criminal charges, even when there is probable cause, if they determine that there is no reasonable likelihood of conviction.^[17] Prosecutors may dismiss charges in this situation by seeking a voluntary dismissal or nolle prosequi.

In Kentucky, Massachusetts, Pennsylvania, and Virginia, criminal prosecutions are brought in the name of the Commonwealth. In California, Colorado, Illinois, Michigan, and New York, criminal prosecutions are brought in the name of the People. In the remaining states, criminal prosecutions are brought in the name of the State.

Prosecutors are typically civil servants who possess a university degree in law and additional training in the administration of justice. In some countries, such as France and Italy, they belong to the same corps of civil servants as the judges.

In Belgium, the Senior Crown prosecutor (Procureur du Roi/Procureur des Konings in trial courts and Procureur Général/Procureur-Generaal in appellate courts) is supported by subordinate Crown prosecutors (substituts/substituten). They open preliminary investigations and can hold a suspect in custody for up to 24 hours. When necessary, a Crown prosecutor will request an examining judge (juge d'instruction/onderzoeksrechter) be appointed to lead a judicial inquest. With a judge investigating, Crown prosecutors do not conduct the interrogatories, but simply lay out the scope of the crimes which the judge and law enforcement forces investigate (la saisine). Like defense counsel, Crown prosecutors can request or suggest further investigation be carried out. The Crown prosecutor is in charge of policy decisions and may prioritize cases and procedures as need be.

During a criminal trial, prosecutors must introduce and explain the case to the trier of fact, i.e., judges or jury. They generally suggest a reasonable sentence which the court is not obligated to follow; the court may decide on a tougher or softer sentence.

Crown prosecutors also have a number of administrative duties. They may advise the court during civil actions.

Under Belgian law, judges and prosecutors are judicial officers with equal rank and pay.

The Minister of Justice can order a criminal investigation but cannot prevent one (droit d'injonction positive/positief injunctierecht).

In Brazil, the public prosecutors form a body of autonomous civil servants—the Public Ministry (Ministério Público)—working both at the federal and state level.

Federal prosecutors (procuradores da República) are divided in three ranks, according to the jurisdiction of the courts before which they officiate. Procuradores da República officiate before single judges and lower courts, procuradores regionais da República before federal appellate courts, and subprocuradores gerais da República before the superior federal courts. The Procurador Geral da República heads the federal body, and tries cases before the Supremo Tribunal Federal.

At the state level, the career is usually divided in promotores de Justiça who practice before the lower courts and procuradores de Justiça who practice before the state courts of appeals. There are also military prosecutors whose career, although linked to the federal prosecutors, is divided in a manner similar to state prosecutors.

In Brazil the prosecutors' main job is to promote justice, as such they have the duty of not only trying criminal cases, but, if during the trial, they become convinced of a defendant's innocence, requesting the judge to acquit him. The prosecutor's office has always the last word on whether criminal offenses will or will not be charged, with the exception of those rare cases in which Brazilian law allows for private prosecution. In such cases, the prosecutor will officiate as custos legis, being responsible to ensure that justice is indeed carried out.

Although empowered by law to do so, prosecutors conduct criminal investigations only in major cases, usually involving police or public officials' wrongdoings. Also, they are in charge of external control over police activity and requesting the initiation of a police investigation.^[18]

The power of individual prosecutors to hold criminal investigations is still controversial and, although massively supported by judges, prosecutors and the general population, it is being contested before the Supremo Tribunal Federal.

According to a 2012 law, the chief of police (delegado de polícia), as the police authority, is responsible for conducting the criminal investigation in Brazil by means of a police investigation (inquérito policial) or other procedure provided by law that has the purpose of ascertaining the circumstances, materiality, and authorship of criminal offenses.^[19] Similar provisions are found in the Code of Criminal Procedure^[20] and in article 144 of the federal constitution.^[21]

Beside their criminal duties, Brazilian prosecutors are among those authorized by the Brazilian constitution to bring action against private individuals, commercial enterprises, and the federal, state and municipal governments, in the defense of minorities, the environment, consumers, and the civil society in general.

In France, the Office of the Prosecutor includes a Chief Prosecutor (Procureur de la République in trial courts and procureur général in appellate courts or the Supreme Court) and his deputies and assistants (avocats généraux and substituts). The Chief Prosecutor generally initiates preliminary investigations and, if necessary, asks that an examining judge (juge d'instruction) be assigned to lead a formal judicial investigation. When an investigation is led by a judge, the prosecutor plays a supervisory role, defining the scope of the crimes being examined by the judge and law enforcement forces. Like defense counsel, the chief prosecutor may petition or move for further investigation. During criminal proceedings, prosecutors are responsible for presenting the case at trial to either the bench or the jury. Prosecutors generally suggest advisory sentencing guidelines, but the sentence remains at the court's discretion to decide, to increase or reduce as it sees fit. In addition, prosecutors have several administrative duties.

Prosecutors are considered magistrates under French law, as in most civil law countries. While the defense and the plaintiff are both represented by common lawyers, who sit (on chairs) on the courtroom floor, the prosecutor sits on a platform as the judge does, although he doesn't participate in deliberation. Judges and prosecutors are trained at the same school, and regard one other as colleagues.

In Germany, the Staatsanwalt ("state attorney") is a life-tenured public official in the senior judicial service belonging to the same corps as judges. The Staatsanwalt heads pre-trial criminal investigations, decides whether to press a charge or drop it, and represents the government in criminal courts. He not only has the "professional responsibility" not to withhold exculpatory information, but is also required by law to actively determine such circumstances and to make them available to the defendant or his/her defense attorney. If he is not convinced of the defendant's guilt, the state attorney is required to plead against or in favor of the defendant according to the prosecutor's own assessment.^[22] Prosecution is compulsory if the prosecutor has sufficient evidence to convict.^[23]

In Italy, a Prosecutor's Office is composed of a Chief Prosecutor (procuratore capo) assisted by deputies (procuratori aggiunti) and assistants (sostituti procuratori). Prosecutors in Italy are judicial officers just like judges and are ceremonially referred to as Pubblico Ministero ("Public Ministry" or P.M.).

Italian Prosecutors officiate as custos legis, being responsible to ensure that justice is indeed carried out. They are obligated under the Constitution to initiate preliminary investigations once they are informed or take personal notice of a criminal act—notitia criminis—or receive a bill of complaint. They can direct investigations or conduct them through orders and directives given to (judicial) police detectives, who can make their own parallel investigations in coordination with the Prosecutor. If enough evidence has been gathered in order to proceed, the prosecution is compulsory and it must move from preliminary investigations to initiate trial proceedings.^[24] At trial, the prosecuting attorney has to handle the prosecution but is prohibited from withholding exculpatory evidence, for they have to promote justice, which means that they have the duty of not only trying criminal cases, but, to request the judge to acquit him if, during the trial, they become convinced of a defendant's innocence, or agree that there is no evidence, beyond any reasonable doubt, of his guiltiness.

In appellate courts, the Office of the Prosecutor is called Procura Generale and the Chief Prosecutor the Procuratore Generale (PG). The Procuratore Generale presso la Corte di Cassazione is the Chief General Prosecutor before the Corte di Cassazione, the Supreme Court of Italy.

Prosecutors are allowed during their career to act in the other's stead, but a recent ruling by the Italian Constitutional Court stated that prosecutors, who wish to become judges, must relocate to another region and are prohibited to sit or hear trials that they themselves initiated.

In Japan, public prosecutors kensatsu-kan (検察官) are professional officials who have considerable powers of investigation, prosecution, superintendence of criminal execution and so on. Prosecutors can direct police for investigation purposes, and sometimes investigate directly. Only prosecutors can prosecute criminals in principle, and prosecutors can decide whether to prosecute or not. High-ranking officials of the Ministry of Justice are largely prosecutors.

The highest ranking prosecutor office of the Prokuratura in Poland is the Prokurator Generalny (General Prosecutor)—chief of the Prokuratura Generalna (General Prosecutor Office). The GP has 5 deputies. Structure of Public Prosecutor in Poland is 4-level: General Prosecutor Office --> Appellation Prosecutor Offices (11) --> District Prosecutor Offices (46) --> Regional Prosecutor Offices (326).

Prosecutors are the public officials who are members of the Ministry of Justice.

Prosecutors can conduct crime investigations directly or indirectly. They are responsible for the entire process of investigations and court prosecutions. Since Korean modern law was designed after continental system, the role of Korean prosecutors is similar or identical to that of European equivalents in commanding investigations, determining indictable cases and prosecuting process. Korean prosecutors take pride in successful prosecutions of former presidents(1995) and sons of the incumbent presidents(1997 and 2002). Besides, they have made important contributions to convicting many corrupt high-ranking officials and business leaders.^[25] A prosecutor has the power to prohibit a defendant or an accused individual from departing the Republic of Korea via an "international hold".^[26]

In Sweden, public prosecutors are lawyers who work out of the Swedish Office of Public Prosecutions (Åklagarmyndigheten) and direct police investigations of serious crimes. For all criminal cases, public prosecutors decide arrests and charges on behalf of the public and are the only public officers who can make such decisions. Plaintiffs also have the option of hiring their own special prosecutor (enskilt åtal). The exception is cases concerning crimes against the freedom of the press for which the Attorney General acts as the prosecuting attorney. In court, the prosecutor is not necessarily in an adversarial relationship to the defendant, but is under an obligation to investigate and present information which may incriminate or exhonerate the defendant. The prosecutor is not a judicial officer, nor do they participate in the private deliberations of the court.

Public prosecutors are the only public officers who can decide to appeal cases to appellate courts (hovrätter). Otherwise, appeals are initiated by defense counsel, the plaintiff, their representatives, and other parties to the case (målsäganden). When a case has been decided by an appellate court, the right to appeal to the Supreme Court passes from the case's prosecutor to the Director of Public Prosecutions (Riksåklagaren).

A Public Procurator is an office used in Socialist judicial systems which, in some ways, corresponds to that of a public prosecutor in other legal systems, but with more far-reaching responsibilities, such as handling investigations otherwise performed by branches of the police. Conversely, the policing systems in socialist countries, such as the Militsiya of the Soviet Union, were not aimed at fulfilling the same roles as police forces in Democratic countries.

A Public Procurator is a position in the People's Republic of China, analogous to both detective and public prosecutor. Legally, they are bound by Public Procurators' Law of the People's Republic of China. According to Article 6, the functions and duties of public procurators are as follows:

The Supreme People's Procuracy is the highest office of public procurators in Vietnam.

In many countries, the prosecutor's administration is directly subordinate to the executive branch (e.g., the US Attorney General is a member of the President's cabinet). In some other countries, such as Italy or Brazil, the prosecutors are judicial civil servants, so they have the same liberties and independence which that judges traditionally enjoy.

In other countries, a form of private prosecution is available, meaning persons or private entities can directly petition the courts to hold trial against someone they feel is guilty of a crime, should the prosecutor refuse to indict.

In the early history of England, victims of a crime and their family had the right to hire a private attorney to prosecute criminal charges against the person alleged to have injured the victim.^[27] In the 18th century, prosecution of almost all criminal offences in England was private, usually by the victim.^[28] In Colonial America, because of Dutch (and possibly French) practice and the expansion of the office of attorney general, public officials came to dominate the prosecution of crimes. However, privately funded prosecutors constituted a significant element of the state criminal justice system throughout the nineteenth century.^[29] The use of a private prosecutor was incorporated into the common law of Virginia, but is no longer permitted there.^[27] Private prosecutors were also used in North Carolina as late as 1975.^[30] Private prosecution has been used in Nigeria, but the practice is being phased out.^[31]

Bruce L. Benson's To Serve and Protect lauds the role of private prosecutors, often employed by prosecution associations, in serving the needs of crime victims in England. Radical libertarian theory holds that public prosecutors should not exist, but that crimes should instead be treated as civil torts. Murray Rothbard writes, "In a libertarian world, there would be no crimes against an ill-defined 'society,' and therefore no such person as a 'district attorney' who decides on a charge and then presses those charges against an alleged criminal."^[32]