On the heels of its decision allowing prolonged confinement in an ICE detention center to continue, the U.S. Supreme Court decided to hear arguments in another case about the federal government’s practice or locking up migrants. Every day, the Department of Homeland Security detains roughly 34,000 individuals. At a cost of at least $126 per day per person, ICE spends more than $4 million daily to incarcerate.

In Nielsen v. Preap, No. 14-16326, the Court will decide whether ICE is required to detain migrants who have served their jail or prison time for a laundry list of crimes and have successfully resettled in the community. The federal government argues that Congress mandates their detention. In its petition to the Supreme Court, the government argued that INA § 236(c), 8 U.S.C. § 1226(c), mandates detention of anyone who has been convicted of just about all the crime-based grounds of removal. In the government’s view, almost everyone who is potentially removable from the United States because of a criminal conviction must be detained while an immigration judge decides whether he will in fact be removed.

As with Mony Preap, a refugee who fled to the United States to escape the Khmer Rouge and has been a lawful permanent resident since 1981, often potential removable based on criminal convictions involves minor offenses. Preap was convicted twice of misdemeanor possession of marijuana. Despite his crimes, an immigration judge granted him cancellation of removal which allows him to continue living and working in the United States. Another named plaintiff in the lower court’s decision, Juan Lozano Magdaleno, also a longtime lawful permanent resident, has a firearm possession conviction and a simple possession of marijuana conviction. Five years after he was released from the drug conviction, ICE picked him up and confined him pending removal proceedings. He was later released under the limits on prolonged detention recently overturned in Jennings v. Rodriguez, suggesting he spent at least six months in an ICE prison.

In contrast to the position that the government advocates, the Ninth Circuit—plus numerous federal district courts—have concluded that detention is required only when ICE takes custody of migrants upon their release from criminal confinement. The court concluded that the “when released” clause is a temporal condition on mandatory custody that Congress imposed. As such, there is no wiggle room for interpretation. If ICE doesn’t take someone into custody “when released” from criminal confinement, then it has failed to implement 236(c).

Except for the Ninth Circuit, all the circuit courts to have decided the issue agree with the government’s position, though they have not agreed on the reasoning. The First Circuit split evenly. The Supreme Court will now weigh in on the breadth of detention power that Congress has granted to ICE. Given the size of ICE’s detention system, this is an enormously important prospect. The country’s immigration detention population grew to unprecedented heights under President Obama. Those record-setting years haven’t stopped continued growth. Trump administration officials have expressed a desire to increase the number of people locked up pending immigration court proceedings.

Under Presidents Obama and Trump, government officials repeatedly claim immigration detention protects the public and ensures that migrants appear to removal hearings in immigration court. In Demore v. Kim, 538 U.S. 510, 513 (2003), the Supreme Court embraced these twin rationales, explaining that Congress enacted § 236(c) because it was “justifiably concerned that deportable criminal aliens who are not detained continue to engage in crime and fail to appear for their removal hearings in large numbers.” The government’s petition for Supreme Court review reiterates this view. It claims, for example, that “[t]he Ninth Circuit’s interpretation…ensures that many criminal aliens…will be given bond hearings, and a significant portion of those will be released, thus creating the very risk of recidivism and flight that Section 1226(c) [INA § 236(c)] would otherwise foreclose.”

Both claims are largely red herrings. A wealth of evidence indicates that migrants commit relatively little crime, especially when compared to people born inside the United States. Moreover, most people do appear for their court dates and Congress has at its disposal options to increase attendance that are less invasive and less costly than detention. Lastly, the Ninth Circuit’s interpretation does not mean that migrants cannot be detained. It only means that they are given the opportunity to ask an immigration judge for their release. As it has done for many years, though, the federal government takes the view that if given the chance, immigration judges’ decisions will endanger the public and subvert the immigration courts’ operations.