Enables cysteine-type deubiquitinase activity. Acts upstream of or within protein deubiquitination. Predicted to be located in endoplasmic reticulum membrane and nucleolus. Predicted to be active in cytosol and nucleus. Orthologous to several human genes including USP17L1 (ubiquitin specific peptidase 17 like family member 1); USP17L10 (ubiquitin specific peptidase 17 like family member 10); and USP17L11 (ubiquitin specific peptidase 17 like family member 11).