The head of a private prison group that owns and operates 23 immigration detention facilities said Wednesday that lawsuits over conditions of confinement are “fundamentally unconstitutional.”

GEO Group CEO George Zoley said on a quarterly earnings call that the private prison group currently detains about 21,000 people in Immigration and Customs Enforcement custody, which is about one-third of all ICE detainees. Detainees in some of those facilities have sued GEO Group and the federal government, alleging they are being held in unconstitutionally inhumane conditions.

“There has been litigation regarding overseeing of medical services, food services, general cleanliness, etc. It’s really unprecedented and, I believe it’s fundamentally unconstitutional,” Zoley said in remarks first reported by The Carceral Report.

GEO Group did not respond to an email asking what, specifically, is unconstitutional about the lawsuits.

In one ongoing suit against GEO Group, current and former immigration detainees in Aurora, Colorado, allege they were required to either clean the facility for no pay or risk being sent to solitary confinement. Detainees who participated in a voluntary work program were paid $1 per day for tasks such as preparing food and doing laundry. GEO has unsuccessfully argued that it should be immune from such litigation because it was acting as a contractor for the federal government.