Mental Health Act 2025 - Practical considerations and how to prepare for changes from a local government perspective

The Mental Health Act 2025 (“the Act”) received Royal Assent on 18 December 2025, marking the most substantial reform to mental health legislation in England and Wales since the Mental Health Act 1983. The Act introduces a number of significant changes to the legal framework governing the detention, treatment and care of people with mental illness(es), underpinned by four core principles: choice and autonomy, least restriction, therapeutic benefit, and the person as an individual. 

For local authorities, the reforms bring a range of new duties and responsibilities spanning some of the most operationally challenging areas of local authority work, such as section 117 aftercare, Approved Mental Health Professional (AMHP) services, advocacy commissioning, and more. Implementation is expected to be phased, with the Local Government Association estimating that duties for councils are likely to commence from 2026/27 and full roll-out is anticipated over a number of years and potentially taking a decade to complete.

This article outlines the key changes relevant to local authorities and considers the practical steps that they may wish to take in preparing for implementation.

New detention criteria

The threshold for detention will be raised. Under both section 2 (admission for assessment) and section 3 (admission for treatment), detention will only be justified where there is evidence of a risk of ‘serious harm’ to the individual or to others.

Autistic people and people with a learning disability will also no longer be lawfully detained for treatment unless they have a co-occurring ‘psychiatric disorder’ meeting the detention criteria. 

Detention periods under section 3 will also be shortened (with, for example, the initial period being reduced from six months to three months). 

These changes place demands on AMHPs who will need to be trained in preparation for the new criteria coming into force. Local authorities should review and refresh any existing training materials to make sure that AMHPs understand how to apply the revised detention threshold; and amend internal decision-making templates to promote defensible assessments.

Section 117 aftercare

Section 117 of the Mental Health Act 1983 places a joint duty on local authorities and Integrated Care Boards (ICBs) to arrange free aftercare for individuals following discharge from detention under section 3. The 2025 Act introduces new ordinary residence “deeming” provisions: under the new rules, where a person is placed out of area, responsibility will rest with the authority that arranged the placement – not the authority in whose area the person happens to be living afterwards. 

The Mental Health Tribunal will also acquire enhanced powers to make recommendations to section 117 bodies regarding aftercare planning ahead of discharge, with the ability to reconvene if those recommendations have not been followed. 

The duty to provide aftercare may only be brought to an end by the formal service of a joint written notice issued by the responsible s117 bodies.

Local authorities that commission out-of-area placements may therefore see changes in their section 117 cost exposure. The new Tribunal powers also mean that local authorities could be required to attend before the Tribunal to explain their position where aftercare arrangements are delayed or not progressed appropriately. To prepare for these changes, local authorities may wish to review existing discharge planning processes to ensure that aftercare packages can be implemented promptly if the Tribunal makes recommendations. 

Places of safety

Under the Act, neither prisons nor police cells may be used as a ‘place of safety’ for adults in mental health crisis. Although custodial settings account for a relatively small number of ‘places of safety’, their removal will place additional strain on healthcare-based places of safety. Local authorities should engage with their ICB partners to assess whether existing places of safety in their area are sufficient to meet anticipated demand before the change takes effect.

The ‘Nominated Person’ and extension of access to IMHAs

In England, the Act now extends access to Independent Mental Health Advocates (IMHAs) to informal (voluntary) patients for the first time. It also introduces an ‘opt-out’ approach, requiring hospital managers and others to proactively inform advocacy services about qualifying individuals; advocacy services are then required to make contact to check whether the individual wants an IMHA. 

The existing ‘nearest relative’ role is also replaced by the new ‘nominated person’ (NP) role. Where a patient has capacity, they may choose their own NP; where they do not, an AMHP will appoint one – and in some cases, a local authority may need to ‘step in’ to act as the NP. NPs will carry enhanced rights, including rights to be consulted about Community Treatment Orders (CTOs), care and treatment plans, and hospital transfers. 

The shift to an opt-out IMHA model is likely to generate a higher volume of referrals, and local authorities should review their commissioned advocacy capacity in advance of implementation. AMHP teams will also need updated training on the appointment process for NPs. Clear internal guidance on the rights and consultation entitlements that come with the NP role will also be crucial. 

Automatic referrals to the First-tier Tribunal (Mental Health)

Section 2 patients will be able to apply for a review of their detention within 21 days of detention – a week longer than the current 14-day period. Section 3 patients can apply within three months of detention (instead of six months). Where a patient does not exercise their right to apply, the Act provides for automatic referrals to be made: first at three months from when the individual was detained, and then at yearly intervals thereafter. 

Local authorities should assess whether existing capacity is sufficient to absorb the additional workload that is likely to be brought about by the increased volume and frequency of Tribunal hearings. High-quality recordkeeping will be essential, given the greater frequency with which social work records and care documentation may be subject to Tribunal scrutiny. 

How we can help

The Act is likely to require local authorities to make substantial operational, commissioning and workforce changes, and local authorities that delay action risk being underprepared when key provisions take effect. We act for local authorities across a wide range of mental health law matters and understand the practical and legal pressures that local authorities face in this area. If you would like to explore how the Act may impact your organisation or how we can support you with implementation planning, please do not hesitate to get in touch with Nicole Ho, Solicitor, or Stuart Marchant, Partner.

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