High Court Decision on inconsistent obligations between the Mental Health Act and Common Law Duty to Others
On 12 November 2014 the High Court unanimously allowed appeals by the Local Health District, represented by TressCox Lawyers, in the cases of Hunter and New England Local Health District v McKenna; Hunter and New England Local Health District v Simon  HCA 44.
The High Court’s decision is significant because it resolves a question of inconsistent duties in the context of a patient requiring psychiatric treatment who has been involuntarily admitted to hospital under the provisions of the Mental Health Act and a potential common law duty to other persons.
In this case, the conflict was between a statutory obligation to discharge an involuntary patient if ‘care of a less restrictive kind is appropriate and reasonably available’ and the pleaded common law duty of care to protect another person from harm caused by discharging the patient.
Mr Pettigrove had a long history of chronic paranoid schizophrenia for which he received treatment in Echuca, Victoria. His schizophrenia was never associated with violence.
Mr Pettigrove was in Taree with his friend Mr Stephen Rose in July 2004 when he suffered an acute psychotic episode that manifest in a semi comatose state. Mr Rose called the ambulance and Mr Pettigrove was taken to Manning Base Hospital.
Doctors at the hospital formed the view that Mr Pettigrove was a ‘mentally ill person’ for the purposes of section 9 of the Mental Health Act and he was detained as an involuntary patient.
The following day Mr Pettigrove became responsive again with treatment. The psychiatrist spoke with Mr Pettigrove, his mother and Mr Rose and they agreed that Mr Pettigrove should be discharged and return to Echuca to continue his medical treatment. They agreed that Mr Pettigrove would be kept in the hospital overnight and that Mr Rose and Mr Pettigrove would drive back to Echuca where Mr Pettigrove would continue his medical treatment.
As planned, Mr Pettigrove was discharged from the hospital the next day. During the journey to Echuca, Mr Pettigrove killed Mr Rose. Mr Pettigrove subsequently committed suicide.
Mr Rose’s mother and two of his sisters sued for damages for psychiatric harm. They alleged that the Hunter and New England Local Health District was negligent because it placed Mr Pettigrove into Mr Rose’s care for the trip to Echuca.
The Local Health District was successful at first instance in the District Court on foreseeability, breach of duty and causation. This decision was overturned by the Court of Appeal. The Local Health District then obtained special leave to appeal to the High Court.
The High Court’s Decision
The High Court heard submissions on whether the Local Health District owes a duty to take reasonable care to protect other people from harm when deciding whether to discharge (or no longer detain) a patient who has been involuntarily admitted under the Mental Health Act.
The High Court placed significant weight on the wording of section 20 of the Mental Health Act:
‘A person must not…continue to be detained in, a hospital…unless the medical superintendent is of the opinion that no other care of a less restrictive kind is appropriate and reasonably available to the person’. 
This provision is consistent with the stated objective of the Mental Health Act to ensure that ‘any restriction on the liberty of patients…and any interference with their rights, dignity and self-respect are kept to the minimum necessary in the circumstances’. 
In this case, it was agreed by Mr Pettigrove, his mother, Mr Rose and the psychiatrist that Mr Pettigrove would return to Echuca to continue his medical treatment. This means that ‘care of a less restrictive kind’ than an involuntary admission to hospital was available. Accordingly, the hospital had an obligation under section 20 of the Mental Health Act to not continue to detain Mr Pettigrove.
The High Court held that the Local Health District could not comply with its obligations pursuant to section 20 of the Mental Health Act and owe a common law duty of care to have regard to the interests of people who may come into contact with a mentally ill person after their discharge from hospital.
The High Court relied on the decision of Sullivan v Moody  in its reasoning about inconsistent duties. In circumstances where it is argued that a doctor or hospital may owe inconsistent obligations to a patient and another person, then ‘that would ordinarily be a reason for denying that the duty exists’. 
In summary, the Mental Health Act determined the powers and responsibilities of the Local Health District when treating Mr Pettigrove as an involuntary patient. It would be inconsistent to find that the Local Health District could comply with its obligations under the Act, but also owe a duty to protect persons other than the patient. Therefore the Local Health District did not owe a duty of care to protect other people from harm when deciding whether to discharge a patient who had been involuntarily admitted.
The High Court’s decision provides some clarity about the obligations of health practitioners when making difficult decisions about the management of involuntary patients. It is clear that the requirements of the Mental Health Act, and equivalent legislation in other jurisdictions, particularly the obligation not to deprive a person of their liberty takes precedence over the potential risk of harm to other persons.
Whilst the Mental Health Act has been amended in NSW, the overall objectives of the Act to limit deprivation of a patient’s liberty remains, as does the obligation to not detain a patient if care in a least restrictive environment is available.
This decision also reinforces the general principle that a statutory duty will often operate to the exclusion of an inconsistent alleged common law duty of care.
 Mental Health Act 1990 (NSW) s20 (repealed). Please see the Mental Health Act 2007 (NSW) s12(1)(b)
 Mental Health Act 1990 (NSW) s4(2)(b) (repealed). Please see the Mental Health Act 2007 (NSW) s68(f)
 (2001) 207 CLR 562
 (2001) 207 CLR 562 at 582 
Natalie Meadows, Partner