Why is ICE’s data on solitary confinement so messy?

U.S. Immigration and Customs Enforcement records the number of immigrants sent to solitary confinement each month. Its data tracking has improved over the years, but much is still missing.

Since April 2024, when the data tracking started, 19,500 detainees have been sent to solitary confinement, or “segregation,” as ICE calls it.

ICE claims it does not use “solitary confinement” because people get access to certain privileges like recreation and telephones in “segregation.”

But detainees sent to segregation describe it as being isolated in a cell without meaningful human interaction for 22 hours a day or more, which is how the United Nations defines solitary confinement.

About 3,400 of the 19,500 sent to segregation were considered part of the “vulnerable and special population,” which ICE tracks more detailed data on. That includes people who have serious mental or medical illnesses, are on suicide watch, are conducting hunger strikes, or may be susceptible to harm in the general population.

The data on vulnerable detainees goes back further: An additional 2,900 vulnerable detainees were sent to solitary confinement from January 2022 to March 2024. That brings the total number of people that ICE has publicly reported sending to "segregation" up to 22,400 since January 2022.

But that figure misses hundreds, if not thousands, of short solitary confinement stays that were hidden from the publicly reported data during former President Joe Biden’s administration.

ICE's solitary confinement reporting requirements changed Dec. 6, 2024, shortly before President Donald Trump took office.

The previous policy required reporting of anyone who spent more than 14 days in “segregation” or anyone with special vulnerabilities who spent more than 72 hours in “segregation,” according to former ICE official Claire Trickler-McNulty. Now, all segregation placements, regardless of length, must be recorded by ICE.

When this change happened, the reported number of people sent to solitary confinement spiked from 550 in November 2024 to 990 in January 2025, an 80% increase.

Because of the timing of this reporting change, ICE’s use of solitary confinement under Biden and Trump cannot be directly compared — a severe data limitation.

The use of solitary confinement expanded initially under Trump, reaching an all-time high of 1,151 in August 2025.

But the figures have dropped since then, back down to 870 people in March 2026. It’s unclear whether this represents more or less frequent use of solitary confinement than under Biden.

Missing data

And although the segregation reporting has improved, the data still do not paint a full picture of the use of solitary confinement in U.S. immigration detention.

The month of September 2025 is missing. ICE declined to answer a question about why this is the case.

“Questions about data that isn’t found online will need to be FOIA’d,” Department of Homeland Security spokesperson Yasmeen Pitts O'Keefe said in an email.

The ICE data includes solitary confinement placements in about 90 different detention facilities, but ICE says it has about 220 detention facilities.

It’s possible that those additional facilities do not use solitary confinement, and that’s why they’re not reporting it. But the sheer number missing, as well as the types of facilities absent, suggest that those missing use segregation but fail to report it.

Most of the detention facilities with no segregation data, about 85 facilities, are U.S. Marshals Service facilities. The Department of Justice contracts with them, and ICE is allowed to use the facilities through a rider, said Claire Trickler-McNulty, a former ICE official.

That means the Marshals facilities don’t have a direct contractual relationship with ICE and likely don’t have to follow ICE’s reporting requirements.

ICE declined to answer a question about whether these facilities are required to report segregation placements.

Trickler-McNulty said “it’s probably hit or miss” whether those U.S. Marshals Service facilities report segregation placements. At any given time, ICE data shows those 85 facilities hold roughly 4,000 ICE detainees — who may or may not be getting sent to solitary confinement on a regular basis.

An ACLU lawsuit alleges solitary confinement is used against immigrants in at least one facility that’s missing from ICE’s segregation data: Guantánamo Bay.

ICE started transferring immigration detainees to Guantánamo Bay for holding in February 2025 and has continued housing detainees there, despite widespread criticism due to the harsh conditions at the facility.

Detainees who were sent there told the ACLU that solitary confinement was used against them as punishment. But Guantánamo Bay appears nowhere in the segregation data.

Medical isolation ‘probably not reported’

Another piece missing from the solitary confinement data is medical isolation.

People can get isolated from the general population of a detention facility in both the segregation unit and the medical unit.

Kyle Virgien, an ACLU senior staff attorney with the National Prison Project, said some ICE facilities have medical units with a small number of isolation cells to prevent infectious disease outbreaks. The isolation cells are typically air-tight and have a window for medical staff to monitor detainees. The cells are used for medical and mental health crises, including for suicide watch.

The number of isolation cells is usually small, so there is often spillover from the medical unit into the segregation unit, Virgien said. That’s what happened during the COVID-19 pandemic. The medical units ran out of space for all of the COVID-infected individuals and housed the overflow in segregation units, Virgien said.

Virgien said he would consider both medical isolation and segregation to be solitary confinement.

“Anything where someone is held in their own cell by themselves for a significant majority of the day is solitary confinement, no matter what it's labeled,” Virgien said. “And often we see facilities coming up with alternative labels so they can claim they're not holding people in solitary.”

These differing labels make the data tracking messy.

ICE reports the number of people sent to “segregation” each month, not necessarily those who were isolated in the medical unit.

Trickler-McNulty said those in medical isolation are “probably not going to be reported” as part of the segregation count.

Michelle Brané, former Immigration Detention Ombudsman, said “it’s hard to know” how each facility counts medical isolation. She said it could be undercounted, overcounted or not counted at all as segregation, depending on the facility.

So there could be a large number of detainees who are experiencing isolation, but not being tracked.

There’s also limited public data on why people are sent to segregation in the first place. ICE only reports that information for the vulnerable and special population.

From January 2022 to March 2026, 45% of vulnerable detainees were sent to segregation for discipline or a pending disciplinary investigation, 30% for medical or mental health reasons, 20% for protective custody, and 5% for a facility security threat.

For 16,000 detainees, that information is unknown.

Craig Haney, a UC Santa Cruz psychology professor and solitary confinement expert, said solitary confinement is a “dangerous” tool that hurts people. He said it’s important to monitor how it’s being used against immigrants.

"As more and more people are being placed in immigration detention, we as a society have to look more carefully at what's happening to them while they're there,” Haney said.