When the Department of Homeland Security makes the choice to refrain from bringing charges against an undocumented person working at a restaurant or to freeze a removal order for a woman who serves as a primary caregiver to her U.S.-citizen children, the agency is favorably exercising “prosecutorial discretion,” which refers to the decision by DHS about whether to enforce an immigration law against a person or a group of persons. There are more than a dozen varieties of prosecutorial discretion, but in all cases, a person who is protected by it is in a position of immigration “purgatory.”

Prosecutorial discretion exists for economic reasons: DHS has the funds to deport only about 400,000 individuals, or less than 4 percent of the 11.3 million unauthorized immigrants living in the United States, so choices have to be made by the agency about who to target for removal and who to place on the backburner. Prosecutorial discretion also has a humanitarian purpose as it allows DHS to consider a person’s equities, such as long-term presence, advanced or tender age, or family ties.

The legal foundation for prosecutorial discretion can be found in a statute created by Congress called the Immigration and Nationality Act, U.S. Supreme Court opinions, and other sources.  For example, in section 103 of the immigration statute, Congress has delegated the responsibility of administering and enforcing the immigration laws to DHS. Further, the Supreme Court has recognized that “a principal feature of the removal system is the broad discretion exercised by immigration officials. … Federal officials, as an initial matter, must decide whether it makes sense to pursue removal at all.”

Under the new presidential administration, the future of prosecutorial discretion is unclear. In January, President Donald Trump signed two executive orders on immigration, laying out new enforcement priorities and broadening the scope of who may be deported. Under these new executive orders, deportable immigrants who have unresolved criminal charges; have committed acts that constitute a chargeable criminal offense; or who pose a risk to public safety or national security are among those prioritized. Additionally, guidelines released in February by DHS state: “All of those in violation of the immigration laws may be subject to immigration arrest, detention and, if found removable by final order, removal from the United States,” leaving the impression that any person may be a priority. These same guidelines rescind previous DHS documents that offered guidance on prosecutorial discretion.

Despite these major changes to enforcement, the guidance from DHS does suggest that individual prosecutorial discretion may still be exercised on a case-by-case basis, and preserves some policies relating to the practice. One policy that remains is Deferred Action for Childhood Arrivals. DACA enables qualifying noncitizens who entered the United States at a young age to apply for a form of prosecutorial discretion called “deferred action.” Also intact is the “sensitive locations” memo, which instructs DHS to avoid immigration enforcement in places like schools, places of worship and hospitals.

With or without these enforcement orders or statements by DHS, prosecutorial discretion is in many ways inevitable—the government simply lacks the resources to carry out enforcement against every person who may be removable from the United States. However, how prosecutorial discretion is exercised matters. One concern is that instead of using priorities to guide enforcement, DHS will arbitrarily enforce the law against individuals and families who happen to be in the wrong place at the wrong time or other low-hanging fruit. Haphazard enforcement can lead to unintended or unlawful consequences, such as the separation of families and abuses of discretion. Another concern (and a somewhat ironic one) is the selective enforcement of immigration laws against particular communities. Whereas the current guidance from DHS directs that no category or class of noncitizens are to be exempt from immigration enforcement, the enforcement of immigration laws against communities along lines of race, religion, nationality, or citizenship remain a distinct possibility.

An April 11 article from the New York Times chronicles the stories of lawyers and clients facing enforcement during the course of check-ins with local immigration offices and the mentality of some officers that their job is to deport people, period. If this message—to deport any person an officer encounters during the course of immigration enforcement—is coming from the top, it is deeply troubling. Any training has to include the use of prosecutorial discretion. The importance of using prosecutorial discretion fairly is not only consistent with history and law but is crucial to ensuring that compassion toward individuals and families remains part of an otherwise broken and complex immigration system.

Shoba Sivaprasad Wadhia is the Samuel Weiss Faculty Scholar and Founding Director of the Center for Immigrants’ Rights Clinic at Penn State Law: University Park. Her book Beyond Deportation: The Role of Prosecutorial Discretion in Immigration Cases is now out in paperback.