The following change made by the Mental Health Act 2007 is relevant:

• Appropriate treatment test replaces treatability test and applies to all patients under long-term detention 3/11/08

The leading case on the test is Reid v Secretary of State for Scotland (1998) UKHL 43.

The test only applied to psychopathic disorder (and, less contentiously, to mental impairment) and stated that treatment must be "likely to alleviate or prevent a deterioration of his condition".