The decision in Gibbons v Wright remains a cornerstone of Australian law on contractual capacity. The High Court rejected the notion that legal capacity is a fixed, binary state and instead articulated what has become known as the “relative capacity” principle. As explained by Owen Dixon, a person’s ability to enter into a legal transaction depends on the nature and complexity of that transaction, rather than on a global assessment of their mental competence. Capacity depends on what is being asked of the individual. A person might be perfectly able to understand a simple, everyday decision, yet struggle with a complex financial arrangement. The law, at least in theory, adjusts itself accordingly. It asks not whether a person is generally capable, but whether they understand the nature and effect of the particular transaction before them.
Under this approach, a person may be capable of making simple decisions while lacking the ability to understand more complex or high-stakes arrangements. The legal test focuses on whether the individual can comprehend the general nature and effect of the specific transaction at hand. This flexible standard is widely regarded as more humane and realistic than rigid rules that strip individuals of autonomy entirely.
On its face, this “relative capacity” principle is humane. It recognises that people are not defined by their limitations alone. It allows for dignity, for autonomy, for the possibility that even those with cognitive impairments can still make meaningful choices about their own lives. It resists the bluntness of total incapacity.
However, the very flexibility that makes the relative capacity principle attractive also creates significant scope for misuse, particularly in institutional contexts involving substitute decision making bodies such as state trustee agencies.
These bodies are entrusted with managing the financial and, at times, personal affairs of individuals deemed unable to do so themselves. Their mandate is protective. They exist to prevent exploitation, mismanagement, and harm. Yet protection, when filtered through bureaucracy, often carries a quiet preference for control.
Within this setting, the inquiry envisioned in Gibbons v Wright can harden into something far less flexible. Capacity assessments, which should turn on the nuances of each decision, may instead become generalised judgments. A person who has once been found to lack capacity in a complex matter can find that conclusion echoing across all aspects of their life. The question subtly changes. It is no longer, “Can this person understand this decision?” but rather, “Is it safer, simpler, or more efficient for the agency to decide instead?”
This is where the vulnerability of the relative capacity principle reveals itself. Because it depends on discretion, it can be shaped consciously or not by institutional priorities. Risk aversion plays a role. So does administrative convenience. Reassessing capacity in a genuinely decision specific way takes time, expertise, and a willingness to accept that individuals may make choices that carry risk. For an agency tasked with safeguarding assets and avoiding liability, there is an understandable temptation to err on the side of restriction.
The result can be a quiet contraction of autonomy. Individuals may be deemed capable when their agreement aligns with administrative processes, yet incapable when they seek to assert independence. Capacity, in this sense, becomes selective and recognised when convenient, withheld when it is not. Over time, the possibility that capacity can fluctuate or be partial, which lies at the heart of the principle, is overshadowed by a more static and cautious approach.
For those subject to these systems, regaining control can be difficult. Demonstrating sufficient capacity for complex decisions may require evidence that is costly, inaccessible, or judged against an implicitly high threshold. The law says capacity is relative; the system, at times, treats incapacity as enduring.
None of this suggests that the protective role of trustee agencies is unnecessary. There are real risks of exploitation, and real harm that can follow from impaired decision making. The tension between protection and autonomy is genuine and unavoidable. But the balance struck in practice does not always reflect the balance imagined in Gibbons v Wright. The principle was meant to preserve as much autonomy as possible. In application, it can drift toward preserving as much control as possible.
The way forward is not to abandon the relative capacity principle, but to take it more seriously.
That would mean building safeguards around its application. Capacity should be reassessed regularly and independently, not treated as a settled question. Decision making processes should be more transparent, so that individuals can understand how and why conclusions about their capacity are reached. Greater emphasis should be placed on supported decision-making, where individuals are assisted to make their own choices rather than having those choices made for them. And, crucially, the system must genuinely recognise that capacity can fluctuate, and that a person may be capable in one context even if they are not in another.
The relative capacity principle articulated in Gibbons v Wright represents a sophisticated and flexible approach to human decision making. Yet its reliance on discretionary judgment makes it vulnerable to institutional overreach. When applied without sufficient safeguards, it risks becoming a tool not of empowerment, but of control. Ensuring that the principle fulfils its original purpose requires ongoing vigilance, robust oversight, and a genuine commitment to preserving individual autonomy.
29 pages