Involuntary administration of antipsychotic medication to pretrial criminal defendants raises important and controversial questions. These questions arise especially with defendants who have been adjudicated as incompetent to stand trial and who require medication to be restored to trial-competency and return to face their pending criminal charges. This subject has been fiercely debated for decades, but it has received little empirical investigation. We review here the known empirical studies that have looked at the use of involuntary medication for this population of individuals. The following nine conceptual areas are explored: subject selection, definition of 'refusal' and related terms, frequency of refusal, characteristics of refusers, reasons for treatment, reasons for refusal, type and outcome of the review of the refusal, outcome of treatment in the hospital, and outcome of the criminal charges. Relevant findings are reviewed. Methodological limitations call for more research in this area.