John Wadham, director of Liberty:

"People should not be locked up on the basis of what some expert thinks they might do in the future. People should be detained only because they have committed an offence, or because it is necessary for treatment of a mental illness.

"There is a real risk of people being detained on dubious grounds, having done nothing wrong, and with no treatment in prospect. Despite the promised safeguards, the scope for injustice in this situation remains alarming

"This also risks turning our psychiatrists and mental health nurses into prison warders. This can't be a sensible way forward.

"Medical opinion on the nature of Severe Personality Disorder remains so divided; and assessing dangerousness remains an inexact science. While that remains the case, this power creates too high a risk of serious injustice".