Thousands of migrants put in solitary confinement without violating any rules

Gallagher also described the misconduct within solitary confinement as "urgent and at times life-threatening."

Details: A review of thousands of documents from 2012 to 2017 — retrieved by the International Consortium of Investigative Journalists with the Freedom of Information Act — included detention records and court fillings, as well as interviews with current and former detainees from around the world.

Their findings included:

• Many of the detained migrants are reportedly disabled, mentally ill or identify as LGBTQ.
• Immigration and Customs Enforcement attributed much of the use of solitary confinement on vulnerable people to safety concerns. However, internal guidances require detention officials to record alternatives considered before resorting to isolation. Gallagher claims she often saw no evidence that ICE had pursued other options.
• In isolation, detainees are on lockdown for at least 22 hours each day.

• Detainees only had attorneys in 11% of the cases.

The United Nations has characterized the use of solitary confinement as "torture or cruel, inhuman or degrading treatment," adding that confinement for 15 or more days should be banned, barring rare circumstances.

Go deeper: Jail can be a death sentence for the mentally ill