spit diaper
A partial facemask put on prisoners who have a nasty tendency to spit or hawk loogies at the arresting officer(s), courtroom inhabitants (judge, bailiff, prosecuting attorneys, jury members, court reporter, etc.), prison employees, and so on. Spit diapers fit relatively tightly over the mouth & nose of the offending spitter, and are fastened to the face with thin elastic bands that fit around the ears.
Eduardo kept spitting at the cops, so they gave him a spit diaper right after he had his mugshot.