A Homeland Security Investigations officer guards workers detained in ICE raids of agricultural processing plants across Mississippi. (U.S. Immigration and Customs Enforcement/AFP/Getty Images)
Joyce White Vance, a former U.S. attorney in Alabama, is a professor at the University of Alabama School of Law.

Federal prosecutors have broad discretion to choose what cases they will bring. Federal criminal law is expansive, and prosecutors’ resources are limited. It would be impossible to charge every single instance of criminal conduct that takes place. So a chief responsibility of prosecutors is a wise exercise of their discretion — what cases do they investigate, whom do they charge.

No universal formulation spells out how they should accomplish this. At its most basic, the responsibility means charging the most serious cases, the ones that affect community safety or integrity, and directing time and resources to those cases. But there is no one-size-fits-all for determining which cases matter the most. Prosecutors must exercise their discretion to focus on individuals who are the most culpable and whose conduct presents the most serious threat.

This brings us to Wednesday’s workplace raids by ICE in Mississippi. We saw hundreds of federal agents descending on plants where poultry is processed. For 680 people who had shown up to work that morning, the day was spent figuring out whether they were legally present in this country or not. Buses whisked away those who could not prove they had lawful immigration status.

It is not a crime to be illegally present in this country. Illegal entry can result in civil penalties or be charged as a misdemeanor or, in repeated instances, a felony, although it was rarely charged criminally before the current administration. Federal criminal law comes into play when someone illegally reenters the country after a previous deportation. The statute, 8 U.S.C. 1326, creates two broad categories of people. Any deported person who returns to the United States without permission from the attorney general faces a maximum penalty of two years in custody. The second category involves what prosecutors often refer to as aggravated reentry. People who return to this country and have three or more misdemeanor convictions or one felony conviction face a maximum sentence of 10 years in custody. Those who have been convicted of serious felonies, like murder, rape, sexual assault of a minor or some types of drug trafficking, face a 20-year penalty. Enhanced sentences apply for people who have committed serious violations.

More than 10 million people are in the country without legal status, estimates say. Even if they thought it was a good idea, prosecutors do not have the resources to charge them all. It took months to plan the Mississippi raids, according to ICE officials. And a single criminal case can take months to investigate, indict and prosecute to conclusion. Immigration offenses are not the only crime federal prosecutors must deal with. Their jurisdiction includes terrorism, cybercrime, public corruption, white collar crime, civil rights violations, drug and gun trafficking, violent crime and human trafficking. U.S. attorneys, in each of the country’s 94 districts, must weigh the need for and the impact of the many potential prosecutions they could possibly bring, because they will need to choose.

Early in my tenure as a U.S. attorney in the Obama administration, I was approached about conducting an ICE raid, very similar to those executed in Mississippi, on poultry plants in northeast Alabama. My first question was whether agents were building a case against the employers. There had been media reports of advertising in Central American countries that directed residents interested in finding jobs in the United States to cities like Albertville, Ala. I was told we did not have a case on the employers in the works; that it was unlikely we could make one because of difficulty in proving intent. So what exactly were we doing, I asked? The plan was to round up workers, determine who was present in the U.S. with authorization and who wasn’t, and detain those who did not have legal status. There would be potential prosecutions of people who had reentered the country after a prior deportation. I asked if we expected high numbers of people who had a history of crime or violence and had reentered the country after being deported in violation of federal law — “aggravated” offenders. Because of the large number of workers at such plants and the difficulty in knowing who they all are before they are detained, it was unclear.

That raid never took place in my district. We had serious cases involving public corruption, violent crime, drug trafficking and civil rights in progress. I did not see how it would be a wise use of our resources to pull away from crimes that were affecting our community in visible ways to arrest people who, while they might have lacked legal immigration status, were going to work every day. We do not prosecute everyone who violates our drug laws, our theft laws, or even our public corruption laws. It did not make sense to redirect our resources in this way.

It was painful watching children in Mississippi this week, presumably American citizens, who were left behind after the raids. These children went off to their first day of school and came home to empty houses with locked doors. None of this should comport with our sense of who we are as a country built on immigration. But in addition to the immediate sense that these raids didn’t represent justice — and our outrage that they were conducted before the people targeted by a hate-fueled shooter in El Paso because they were Hispanic could even be buried — there looms the question of whether government action like this has more to do with politics than prosecution.

What warrants this type of intentional display of intimidation? The Department of Homeland Security, which oversees ICE, has the authority to conduct audits, and it could have done that here, using a process to hold the real culprit, the employer, accountable. Perhaps prosecutors are still planning a prosecution of that type, but from an investigative standpoint, it makes more sense to complete that investigation and take action against the employer before tipping prosecutors’ hand, not to mention rounding up and deporting hundreds of potential witnesses. Nonetheless, on Wednesday, 600 federal agents spent their day arresting people at their place of work, and now more agency resources will be expended, as well as those of courts and prosecutors. The question is, at what cost to prosecutions that might have better served the community than removing parents from children — children that the parents were hard at work for, so they could help them grow into productive citizens.