The Mason Inquiry (Mason et al., 1998) established the service principle that people with a serious mental illness in prison in New Zealand have the same right of access to mental health services as anyone in the community. This includes the access to inpatient treatment if acute admission is required. Recent work on psychiatric morbidity in New Zealand prisons (Simpson et al., 1999; Brinded et al., 2001) has confirmed that there are perhaps 200 people with acute mental health treatment needs in prison. Over-demand for forensic inpatient beds has created waiting lists for prisoners to get access to inpatient treatment, many of whom are incompetent to make treatment decisions. Should such people have the same “right” to access compulsory community treatment as others in the “community”? The Mental Health (Compulsory Assessment and Treatment) Act 1992 (NZ) (the Act) allows for the continuation of compulsory treatment in prison of a remand prisoner already under such an order at the time of arrest, but once sentenced, compulsory treatment can only be initiated by transfer to hospital. The ethical and practical issues that emerge from this legal and service context are examined. The difficulties inherent in compulsory mental healthcare in prison exceed any benefits that might accrue from its use.