A Local Authority was found liable to pay damages in compensation for unlawful detention under s.3 of the Mental Health Act 1983 (the Act) as the patient’s brother had objected to the admission. The Local Authority and not the NHS Trust was found to be responsible for the actions of the approved mental health practitioner (AMHP) despite the Trust detaining the patient – TTM (by his litigation friend TM) v London Borough of Hackney and East London NHS Foundation Trust 14.01.11(CA).

TTM appealed against a judicial review decision that detention was lawful and he had no reasonable prospect of success in any negligence claim. TTM was admitted to East London NHS Foundation Trust (second respondent) under s.3 of the Act. The application for admission was completed by a social worker (AMHP) employed by London Borough of Hackney (first respondent). TTM’s brother objected to the admission, although the AMHP mistakenly believed the brother had agreed to the detention. TTM was granted a writ of habeas corpus on the basis that while the AMHP honestly believed the brother did not object, the fact he did object meant detention was unlawful. A key question was whether the Trust (a ‘second actor’) would be liable for the unlawful detention or the Local Authority.


TTM’s detention was unlawful and had no justification despite the AMHP acting in good faith. The Trust acted in complete good faith under s.6(3) of the Act. That section obliges a Trust and its managers to admit a patient under a Mental Health Act section where an application for their detention appears to have been duly made. The Court of Appeal clarified that the Local Authority, through the AMHP, has responsibility for ensuring any application for a patient’s detention is lawful and that the Trust’s responsibility is in carrying out that detention on the application of the Local Authority, provided the application appears in order. The case brought to light s.145 (1AC) of the Act in that the AHMP acts on behalf of the local social services authority and that it is vicariously liable for any lack of care or bad faith on the part of the AMHP. It also highlighted that one of the social services functions of a local authority is to appoint AMHPs.


Local authorities must be vigilant to the fact they are responsible for the actions of AMHPs who may also work in or closely with NHS Trusts. There must be a robust system of checks and balances in place to ensure the correct application of the Act, to include correct completion of prescribed forms and applications for detention. Trust managers must maintain vigilance in ensuring all applications are duly completed.

TTM provides Trusts with an additional defence against claims brought for wrongful acts by AMHPs, where they are employed by local authorities and there are no complicating factors. In such circumstances, AMHPs may be liable for their actions. TTM does not mean all responsibility for a patient’s unlawful detention rests solely with AMHPs and local authorities. Each case must be considered on its merit and there are likely to be many instances where liability rests either jointly with the local authority or solely with the Trust.

Given the risk of increased claims liability, local authorities are encouraged to scrutinise existing and potential claims with Trusts to assess likely exposure. In addition, service level agreements in place between Trusts and local authorities for the provision of AMHP services should be scrutinised to determine liability for action.