The majority of crimes are prosecuted by lawyers who hold local (mostly county, but sometimes city) positions. This type of prosecutor is frequently known as a district attorney (DA), but in some places as a prosecuting attorney, state’s attorney, or county attorney. In most jurisdictions, the public elects district attorneys. Most district attorney offices are responsible for prosecuting felony and misdemeanor crimes committed in their jurisdictions, although some places have separate prosecutorial offices for misdemeanors and felonies. The U.S. Department of Justice, which is divided into 93 federal districts, prosecutes federal crimes.

After someone has been arrested (and possibly detained) on suspicion of committing a crime, a prosecutor must decide whether to file charges. He or she determines whether there is sufficient cause by reviewing information contained in the arresting officer’s complaint. The prosecutor looks in particular at the quality of evidence presented—and at other factors surrounding the incident. He or she may increase, reduce, or dismiss the charges brought by the police. In some cases, the prosecutor may request more information from law enforcement or investigators before making a final decision.

In most circumstances, prosecutors enjoy broad discretion and affect the trajectory and outcome of criminal cases more than other actors in the justice system do. An analysis ofprosecutorial decision making conducted by the Vera Institute of Justice found that while prosecutors’ decisions are guided by criminal statute, other factors influence the charging process. For instance, restricted resources, such as limited court hours, may prompt a DA’s office to prioritize some charges over others, dismissing those of lower priority.

Plea bargains, which prosecutors have the discretion to offer to defendants, are ubiquitous in the U.S. criminal justice system. In fact, very few criminal cases make it to trial, where a judge and jury are the primary decision makers. An estimated 94 to 97 percent of cases end in a negotiated plea bargain, a process in which the prosecutor retains much of the negotiating power. These negotiations vary from individual to individual, from office to office, and from jurisdiction to jurisdiction, so that cases involving similar charges and even similar defendants may have decidedly different results.

Research shows that people who are in custody before their trials are more likely to accept plea bargains and are less likely to have their charges dropped by prosecutors. For some defendants held in jail during the pretrial phase, including those who pose little threat to public safety but are too poor to afford bail, a guilty plea is the fastest way to resolve their cases and get out of jail—even though a guilty plea will also saddle them with the myriad collateral consequences of a criminal conviction. In this way, jail detention can serve as a powerful leverage mechanism for prosecutors, placing poor people at greatest disadvantage.

Plea bargains can also exacerbate racial disparities in the criminal justice system. Studies have shown that African Americans are less likely to receive reduced charges and reduced sentences than are white defendants who accept plea bargains. Vera’s study of race and prosecutorial decision making in the New York County District Attorney’s Office found that black and Latino defendants were more likely to be detained in jail at arraignment and receive a sentence of incarceration with their plea bargains than similarly situated white defendants were.

Frequently elected on tough-on-crime platforms, prosecutors have historically been judged by how high their conviction rates are. However, prosecutors in growing numbers are broadening the scope of their role in their communities by integrating more holistic measures of success—such as declining crime rates and positive community relations—into internal performance metrics.

Many prosecutors are using their discretionary power to help reduce the use of incarceration and improve outcomes for people involved in the justice system. For example, many jurisdictions now have diversion programs that require certain defendants—often those who are assessed to be at low risk of reoffending and suffer from substance use disorders or mental illness—to undergo community-based treatment and/or abide by other conditions, such as staying arrest-free for a designated period of time in lieu of criminal prosecution. Some programs intervene before formal charges have been filed—known as pre-charge or pre-filing diversion programs—while others occur once charges are filed (a post-charge program), though charges may be dropped or reduced if defendants successfully complete the program. Some post-charge programs require an individual to plead guilty upon admission.

As an example of how perceptions of the prosecutor’s proper role are shifting, more than 150 current and former law enforcement leaders—police chiefs, prosecutors, sheriffs, and attorney generals—formed the group Law Enforcement Leaders to Reduce Crime and Incarceration. They have committed themselves to providing leadership in four broad areas of reform: 1) increasing alternatives to arrest and prosecution—especially diversion to mental health and drug treatment; 2) restoring balance to criminal laws; 3) reforming mandatory minimum sentencing laws; and 4) strengthening community–law enforcement relations. Similarly, the National Network for Safe Communities, a project of John Jay College of Criminal Justice, and the District Attorney of New York County recently established the Institute for Innovation and Prosecution (IIP). IIP aims to serve as a think tank for prosecutors and other criminal justice experts to explore and promote prosecutorial practices that reduce unnecessary incarceration, reduce crime, and foster public trust in the U.S. justice system.