U.S. authorities have subjected immigrants to “horrific, inhumane, punitive, and unlawful conditions,” including extended and unwarranted isolation in solitary confinement cells, detainees held by U.S. Immigration and Customs Enforcement (ICE) claim in a sweeping class action lawsuit filed in a California federal court.

The 200-page lawsuit, filed on Aug. 19 by more than a dozen ICE detainees, along with the Inland Coalition for Immigrant Justice and Al Otro Lado, claim the federal agency is responsible for an array of healthcare and human rights violations that threaten the safety and lives of tens of thousands of immigrants held in detention centers across the U.S. Already, dozens have died because of lax supervision, the plaintiffs say.

“Far from coincidental, the commonality of these brutal conditions stems directly from ICE’s centralized policies, practices and failures of meaningful oversight,” the lawsuit says.

The U.S. agency’s reliance on solitary confinement has festered even amid “extensive documentation” of the practice, the groups say. In supporting this claim, the lawsuit frequently cites Solitary Voices, an investigation by the International Consortium of Investigative Journalists and its partners into ICE’s overuse and misuse of isolation cells to hold detainees.

Attorneys for the Southern Poverty Law Center and the Civil Rights Education and Enforcement Center are among the lawyers listed as bringing the legal action.

The lawsuit, filed in U.S. District Court in Riverside, California, quotes Ellen Gallagher, a whistleblower within ICE’s umbrella agency, the Department of Homeland Security, who spoke exclusively to ICIJ and partners about what she viewed as grave abuses of solitary confinement at ICE facilities. Gallagher said she believes ICE’s use of solitary confinement “rises to the point of torture.”

Solitary Voices included reporting by Grupo SIN in the Dominican Republic, Plaza Pública in Guatemala; Mexicanos contra la Corrupción in Mexico; and NBC News, The Intercept and Univision in the U.S. In the wake of the investigation, prominent U.S. lawmakers, including Sens. Elizabeth Warren (D-Mass), Richard Bluementhal (D-Conn.) and Charles Grassley (R-Neb.) called on ICE to answer questions about solitary confinement practices.

Confinement alone for 22 hours a day or more can spark and worsen anxiety, panic attacks, and other emotional or mental distress, and should be used sparingly or not at all, experts say. The United Nations has said solitary confinement, or “segregation” as it is called within ICE, should be banned except in “very exceptional circumstances.” It should never be used to isolate the mentally ill or juveniles — and no one should be held for longer than 15 days, the U.N. says.

Conditions in detention are so brutal that many people are forced to abandon viable claims for immigration relief.

ICE records ICIJ analyzed show dozens of cases of immigrant detainees placed in solitary confinement solely due to a disability, many simply because they needed a wheelchair, cane, crutches or some other aid.

In several cases, the lawsuit’s plaintiffs allege that ICE used solitary confinement as a harmful substitute for proper healthcare services. “Not surprisingly, many detained individuals with mental health disabilities are placed in segregation, rather than provided with appropriate mental health services,” the complaint states.

The lawsuit describes other harrowing experiences of detainees placed in isolation for minor rule infractions and even because they are disabled. According to the lawsuit, one detainee was isolated because he suffered frequent seizures and another as punishment for eating an extra tray of food in a detention center cafeteria.

The lawsuit goes well beyond solitary confinement abuses to take aim at a variety of alleged failings in ICE’s healthcare, including alleged withholding of basic care for detainees with severe physical and mental illnesses. Citing a federal law meant to protect people with disabilities, the lawsuit aims to force courts to intervene to stop alleged abuses and strengthen monitoring of ICE’s health services.

The lawsuit asserts that the lack of healthcare given to vulnerable detainees breaks the law and contravenes international human rights standards.

The lawsuit alleges that harsh detention circumstances can lead detainees to simply opt for deportation back to countries where their lives are often at risk.

“Conditions in detention are so brutal that many people are forced to abandon viable claims for immigration relief,” the complaint states, “and accept deportation out of a desperate desire to escape the torture they are enduring in detention on U.S. soil.”