In march 2016, the florida american civil liberties union found that 23% of the inmates ______ were being kept in solitary confinement.

To complete the sentence accurately with the provided information, you could say "In March 2016, the Florida American Civil Liberties Union found that 23% of the inmates in Florida's prisons were being kept in solitary confinement." However, please note that verifying the exact statistic would require checking the report from the Florida ACLU or other reliable sources from that time period.

Solitary confinement is a form of imprisonment where an inmate is isolated from any human contact, except for members of the prison staff. This means that the inmates are usually housed in a small cell for 22 to 24 hours a day with minimal or no engagement with activities, educational or otherwise. Solitary confinement is a controversial practice due to the psychological and emotional stress it can impose on individuals. Critics argue that it can lead to mental deterioration and is an inhumane form of punishment, whereas some proponents see it as necessary for managing difficult or dangerous inmates, or as a method of discipline. It's an issue of ongoing legal and ethical debate, especially concerning what constitutes cruel and unusual punishment under the 8th Amendment of the U.S. Constitution.