America's prosecutors are out of control.

Consider the case of Brittany Stephens, a young Louisiana mother who was charged with negligent homicide for the death of her 1-year-old daughter, Seyaira. Stephens and her child were riding in an SUV with family friends when they were hit at an intersection by an off-duty police officer driving 94 mph in a 50 zone. The SUV was destroyed, and Seyaira did not survive. Though Stephens was not driving and bears no responsibility for the crash, she was slapped with the exact same charge as the cop whose recklessness killed her little girl — all because she failed to accomplish the herculean feat of properly securing Seyaira's car seat.

This is an unjust charge, a charge that never should have been made. And the reason it has been made is simple: Prosecutors can basically do whatever they want.

Prosecutors in America, most commonly called district attorneys, have enormous and often unaccountable discretion. "They can choose how harshly to go after someone, how lenient to go after someone," explains John Pfaff, a Fordham University professor of criminal law. "They have tremendous power in that respect."

The prosecutor in Stephens' case, East Baton Rouge District Attorney Hillar Moore III, was not obliged to charge her. He did not have to pile a legal fight on top of the horror of losing an infant in a preventable accident. He chose to do so, and district attorneys across the country can and do make similarly cruel and unnecessary choices. They have significant control over whether a case is prosecuted, what charges are brought, whether it goes to trial or is settled out of court, what sentence is sought, and so much more.

This discretion is not inherently negative. In the right hands, it can be used to moderate the excesses of overcriminalization, to hold cops and other public officials accountable, and to offer mercy in extraordinary cases like Stephens' where the result of prosecution will be inhumanity, not deterrence.

But though the prosecutor's power may be used for good, it is still power, and thus still ripe for corruption. It plays a role in the systemic discrimination of our justice system, and at an individual level it is vulnerable to abuses of malice, callousness, ambition, and incompetence.

The prosecutor's power is also allotted at the ballot box. Where other players in the justice system, like police officers and judges, may be appointed or simply hired, district attorneys are typically elected. This arrangement too is of questionable value — it creates a dangerous incentive to aggressive prosecution, especially in election years, to bolster a "tough on crime" image immune to negative advertising — but it does offer a real and relatively quick route to change.

Criminal justice reformers have taken notice. "We're just recognizing how powerful district attorneys are in shaping criminal justice policies, both at the local level, but also at the statehouse," says Taylor Pendergrass of the ACLU's Campaign for Smart Justice. "The lobbying power of prosecutors is really a substantial force almost everywhere we want to see change made in the criminal justice system." While other needed changes in the justice system require institutional adjustments that may take years to accomplish, you only need one election cycle to get a better prosecutor.

In districts across the country, 2018 may be that cycle. In Texas, for example, 13 sitting district attorneys faced a primary challenger this year, and half of them lost. "People are starting to understand ... the DA to them is more important in many ways to their daily life than who's the governor of Texas or who's the president of the United States," explained Rob Smith, executive director of the Fair Punishment Project, which includes "overzealous prosecutors"" among the causes of sentencing dysfunction the organization seeks to address.

The paragon of success in this project may be Philadelphia District Attorney Larry Krasner, who assumed office in January after a decisive victory at the polls. A former civil rights attorney, Krasner ran on a reform platform, vowing to "fundamentally change [the culture of the Philadelphia District Attorney's Office] from a culture of seeking victory for prosecutors to a culture of seeking justice for victims."

He has made good on that promise, releasing a detailed memo overhauling the function of his office. On Krasner's watch, Philly prosecutors will no longer bring any charges for marijuana possession. In petty theft cases, they will focus on restitution. When recommending prison sentences for low-level and nonviolent offenders, they will be asked to justify the cost to local taxpayers. "If you are seeking a sentence of 3 years incarceration, state on record that the cost to the taxpayer will be $126,000.00 (3 x $42,000.00) if not more and explain why you believe the cost is justified," the memo directs, noting that the annual cost of incarcerating a single prisoner exceeds "the average family's total income in Philadelphia in 2017."

It would be better to enshrine these changes in law, but in the short term, Krasner offers a striking example of prosecutorial discretion used for good. Implemented at a large scale, this sort of reform would put an enormous dent in the United States' twin problems of overcriminalization and mass incarceration, as research shows prosecutors' increasing choice to charge misdemeanors as felonies is a major contributor to recent decades' spike in incarceration rates.

If Brittany Stephens' accident had happened in a jurisdiction with a prosecutor like Krasner, it is difficult to believe she would be facing such a shameful charge. For the sake of her case and untold numbers of more mundane situations, electing humane and just district attorneys is a worthy cause.