Legal Article: Use of Force in Relation to Mental ill Health and Capacity

25 March 2020

Written by: Ruth Hartley, PNLD Legal Adviser
Not reviewed after the date of publication

Front line officers regularly come into contact with persons suffering from mental health problems. In such circumstances, officers have an obligation to assess whether a particular individual poses a threat to themselves or the public, and where appropriate, take intervening action to rectify any threat.  Often, this results in officers using physical intervention tactics, equating to use of force.

PNLD Legal Adviser Ruth Hartley examines the relationship between the use of force and the methods of intervention available to officers in the remit of mental health – an area which PNLD are regularly asked to advise on.

Authorised Practice and Legislation

The Authorised Professional Practice issued by the College of Policing outlines that when officers are dealing with individuals suffering from mental health concerns and physical intervention becomes necessary, particular legislative powers can be relied upon. Whilst the most appropriate legislative power will depend on the specific circumstances, the available powers are as follows:

Mental Capacity Act 2005 (MCA):

Section 4B – Deprivation of liberty necessary for life-sustaining treatment.

Section 5 – Acts in connection with care or treatment.

Section 6 – Rules concerning acts intended to restrain persons lacking capacity.

Mental Health Act 1983 (MHA):

Section 136 – Removal of mentally disordered persons without warrant.

Section 135 – Warrant to gain entry to conduct assessment / search for and remove patients.

Please note, when a situation is not deemed to be an emergency requiring physical intervention, officers are expected to make referrals to medical professionals for an assessment of their needs under the Care Act 2014 and / or involve other methods of social intervention and support.

Officers may be able to negate legal liability for committing physical acts when relying on the above provisions but will be expected to demonstrate that any action taken was necessary and proportionate, and taken in line with the National Decision Making Model.

Powers in Practice

PNLD are often asked for advice on the remit of the aforementioned legislative provisions, with officers noting that the powers fail to cater for all of the mental health emergencies encountered during their daily duties. The most regularly cited example of such, is when officers encounter individuals threatening suicide within a private dwelling / residence.

Section 136(1A) MHA has the effect that officers are able to move a person suffering from a mental disorder from any location, other than a private dwelling. However, although in such circumstances, officers would be able to enter a private dwelling under the authority of a warrant granted under section 135 MHA, officers have reported that it is not always practical to obtain a warrant when dealing with a mental health emergency due to the time constraints involved with obtaining such, especially as the information on the warrants oath also needs to be laid by an approved mental health practitioner – an additional time constraint.

Regarding the powers under the MCA, a person (including a police officer) can undertake an act in connection with the care or treatment of another person, if they reasonably believe that the person lacks capacity and the relevant act it is in his best interests. A person can be deprived of their liberty (for example, by the police), but only if it is to enable life-sustaining treatment or treatment necessary to prevent a serious deterioration in the person's condition. However, officers are citing that it is problematic to determine whether or not a suicidal person lacks capacity, for the purpose of the powers being exercised. This is because both the MCA Code of Practice and Authorised Professional Practice in the area, both state that persons demonstrating suicidal ideation may still be deemed to have capacity.

Section 1(2) of the MCA, which deals with whether an individual has capacity, refers to their ability to make decisions, stating that ‘a person must be assumed to have capacity unless it is established that he lacks capacity’. Therefore, the automatic assumption should never be that a suicidal individual lacks capacity, there must be some form of proof for an officer to justify a ‘reasonable belief’ that restraint of an individual is required, pursuant to section 6  of the MCA.

This combination of legislative safeguards, albeit ensuring persons with mental health concerns are adequately protected, has been cited by officers as leaving them uncertain to whether they will be legally protected should they temporarily deprive an individual of their liberty in a particular scenario, believing they are acting in the person’s best interests. 

The question has therefore been put to the courts whether in circumstances where mental health provisions do not apply to a particular situation, officers are able to rely on the separate powers under common law to use force, where necessary?

Case Law

The relationship between the MHA and common law use of force, was considered in the case of R (on the application of Sessay) v South London and Maudsley NHS Trust and Commissioner of Police for the Metropolis 2011. Whilst the specific facts of the case do not concern a suicidal individual, the judgement lends itself to many of the pertinent issues highlighted in this article. The judge concluded that in cases where the provisions of the MHA were applicable and were the most appropriate means in which officers could have intervened, officers were not instead able to justify physical intervention by relying on the common law doctrine of necessity and the general powers bestowed on officers to use force. However, where the provisions of the Act did not apply, the common law defence of necessity and any requisite force arising out of reliance on that, may be justified.

The same point was made ZH v Commissioner of Police for the Metropolis 2012, but in the context of the MCA. Again, this case did not involve a suicidal individual; it involved an autistic male who would not move away from the side of a swimming pool, ultimately resulting in officer intervention. Some of the officers involved in the intervention in this case were not aware of the provisions under the MCA and therefore, had not directly relied on the legislation when considering whether to intervene. Despite this being the case, the judge ruled that this did not preclude the provisions from being directly applicable to the case, as long as officers could demonstrate that they had in fact undertaken the necessary considerations under the Act, at the time of intervention.

The judge clarified that the correct decision making process that should have been exercised by the officers involved, was whether ZH lacked capacity and whether restraining him was a necessary, reasonable and proportionate response. It was the opinion of the judge that the officers had satisfied the requisite conditions and their actions were covered by the Act. However, in the event that officers were unable to demonstrate that the required considerations under the Act had been satisfied, consideration was given to whether the common law defence of necessity would preclude the officers from liability regarding the force used, in the event that the Act did not apply.

The judge explained that where the provisions of the Act applied (even where the officers had not evidenced that was the case) the common law defence of necessity could not also be raised. Parliament could not have intended for the two to co-exist, as the provisions of the Act had been drafted to build on the existing common law position. To allow the common law defence of necessity to succeed because officers had failed to justify that the powers under the MCA were satisfied, was not what Parliament had intended and for the court to permit that to be the case, would likely infringe a person’s Human Rights. However, where the provisions under the Act are not invoked, the common law defence of necessity may still apply.

These two judgements provide clarity on how the legal provisions in this area interact, however there have been no subsequent cases clarifying matters further. It appears that mental health interventions are something which are very much decided on a case-by-case basis.

Additional considerations for officers

As well as considerations specific to the legislation, the World Health Organisation have outlined that officers have a legal responsibility to prevent suicide and that a primary objective of any police force is to protect life. Therefore, an officer acting in a manner that is intended to prevent a person taking their own life or severely harming themselves may potentially be viewed by the courts as that individual acting in fulfilment of their legal obligations as an officer. If however, actions are called in to question, it is the personal responsibility of a specific officer to justify that any use of force (no matter the level) was reasonable and proportionate and it will fall to them to justify this to the relevant court. Once again, it must be stressed that whether the correct action has been taken, is something to be decided on a case by case basis.


Clearly, front line officers have to undertake numerous considerations in pressurised circumstances when deciding on the most appropriate means of mental health intervention. Officers have to ensure that they can demonstrate full consideration of mental health legislation prior to taking any intervening action, especially if they are of the view that use of force may be required in the circumstances. Whilst there has been some suggestion of future reform in this particular area of law, currently the actions taken and force used are the personal responsibility of each individual officer and the courts have demonstrated that they are willing to ask officers to justify as such. Therefore, when dealing with a person an officer has to make an assessment of the situation and be clear upon the power they wish to rely upon – having overall regard to their personal duty to protect life.

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