Substitute Decision Maker Victoria
How Victoria Decides Who Speaks for You
When a patient in Victoria loses the capacity to make their own medical decisions — whether from a sudden stroke, progressive dementia, or sedation during surgery — someone else must step in. The Medical Treatment Planning and Decisions Act 2016 sets out exactly who that person is, and the answer depends on whether you've appointed someone formally or left it to the statutory default.
If you've done nothing, the hospital doesn't simply turn to your "next of kin." Victoria uses a specific legal hierarchy, and the person who ends up making life-and-death decisions on your behalf might not be the one you would have chosen.
The Statutory Hierarchy of Decision-Makers
When no Medical Treatment Decision Maker (MTDM) has been formally appointed, and no VCAT-appointed guardian holds medical authority, the treating clinician must locate the first available and willing person in this order:
- Spouse or domestic partner — includes registered relationships, de facto partners, and same-sex partners. The partner must have a "close and continuing relationship" with the patient.
- Primary unpaid carer — someone who provides regular, ongoing personal care without payment.
- Oldest adult child — age determines priority when multiple children exist.
- Oldest parent — biological or adoptive.
- Oldest adult sibling — again, age breaks ties.
If nobody in the hierarchy is available, willing, or contactable, the treating clinician must apply to the Office of the Public Advocate (OPA), which can act as the decision-maker of last resort under Section 63 of the 2016 Act.
How a Formally Appointed MTDM Overrides the Default
You can bypass the entire statutory hierarchy by completing a formal Appointment of Medical Treatment Decision Maker — a free statutory form available from the Victorian Department of Health. Your appointed MTDM sits at the top of the hierarchy, above your spouse, children, and everyone else.
This matters in several real-world situations:
- Blended families. If you've remarried and want your adult child from a previous relationship (rather than your current spouse) making medical decisions, a formal appointment is the only way to guarantee that.
- De facto partners. Proving a "close and continuing relationship" to a hospital's legal team during a crisis can be stressful and time-consuming. A formal MTDM appointment removes all ambiguity.
- Same-sex couples. While the Act treats same-sex partners identically to opposite-sex partners, a written appointment avoids any potential challenges from extended family members.
- Estranged relatives. If your oldest child or a parent is estranged but technically holds a higher position in the default hierarchy, they could end up making decisions you wouldn't want. A formal MTDM appointment takes that risk off the table.
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What a Substitute Decision-Maker Can and Cannot Do
A substitute decision-maker — whether formally appointed or operating under the statutory hierarchy — must make decisions that are consistent with the patient's known values and preferences. They are required to act in the patient's best interests when those preferences aren't known.
There are firm limits:
- An MTDM cannot override a valid instructional directive. If you've written a binding refusal of CPR in your Advance Care Directive, your MTDM has no authority to consent to CPR. The written directive wins.
- A values directive gives the MTDM interpretive discretion. If your ACD says you value "being able to recognise family" but doesn't give specific treatment instructions, your MTDM decides how that value applies to the medical situation at hand.
- An EPOA attorney cannot make medical decisions. This is the most common point of confusion in Victoria. An Enduring Power of Attorney covers financial and personal/lifestyle matters only — never medical treatment.
When the System Breaks Down
The default hierarchy can create serious problems in practice:
Nobody is available. If a patient is admitted to emergency care at 2 AM and no family member can be reached, clinicians must provide any treatment they believe is necessary to prevent serious deterioration. They're not required to wait for a substitute decision-maker to be located before acting in a genuine emergency.
Family members disagree. When the person highest in the hierarchy refuses to make a decision, or when family members at the same tier disagree, the clinician can apply to VCAT for a guardianship order. While VCAT charges no filing fee for guardianship applications, the process is slow and formal — exactly the wrong pace for an acute medical situation.
The "close and continuing relationship" test. Estranged spouses who are separated but not divorced still technically sit at the top of the hierarchy. A hospital may default to an estranged partner unless someone can demonstrate that the relationship no longer qualifies.
Appointing Your MTDM the Right Way
The appointment form requires two adult witnesses, at least one of whom must be a registered medical practitioner, a lawyer, or a person authorised to witness affidavits. Unlike an ACD, the MTDM appointment can be witnessed remotely via audio-visual link (Zoom or Teams), provided a special witness — a practising lawyer or Justice of the Peace — oversees the session and all participants are physically in Victoria.
Your appointed MTDM must sign the form to accept the role. You can also name an alternative MTDM who steps in if the primary appointee is unavailable or unwilling when the time comes.
The Victoria Advance Directive & Living Will Kit includes the MTDM appointment alongside the ACD, with step-by-step instructions for the witnessing process and a guide for the conversation you should have with your chosen decision-maker before they sign.
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