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The principle of informed consent
Consent to participate in research and evaluation must be voluntary and based on sufficient information and adequate understanding of both the research/evaluation and the implications of participation (NS 2.2.1). This is the guiding principle of NS Chapter 2.2, and every other requirement in the chapter exists to give that principle practical effect.
Consent is not a formality. NS 2.2.4 states that the process of communicating information and seeking consent "should not be merely a matter of satisfying a formal requirement. The aim is mutual understanding between researchers and participants." That aim requires giving participants an opportunity to ask questions and to discuss the decision with others if they wish (NS 2.2.4).
What valid consent requires
Valid consent under the National Statement has the following elements:
- Adequate understanding of the purpose, methods, demands, risks, and potential benefits of the research or evaluation (NS 2.2.2). See Information required for the full list of matters that must be communicated.
- Information presented in ways suitable to each participant, taking account of literacy, language, culture, age, and disability (NS 2.2.3, NS 5.3.6). See Plain language, Easy English and Easy Read.
- A genuine opportunity to consider the decision, ask questions and discuss it with others (NS 2.2.4).
- Freedom from coercion or pressure, whether overt or reflected in deference to a researcher/evaluator's position of power or to someone else's wishes (NS 2.2.9). See Avoiding coercion.
- A clearly established decision to participate, whether or not participants are identified (NS 2.2.7).
How consent may be expressed
Consent may be expressed verbally, in writing, or by some other means, such as return of a survey or conduct implying consent (NS 2.2.5). The appropriate form depends on the nature, complexity, and level of risk of the research, and on the participant's personal and cultural circumstances (NS 2.2.5(a)-(b)). A written participant information sheet is conventional but not mandatory: it is not a requirement of the National Statement that consent must, routinely, be witnessed (NS 3.1.24).
Whatever strategy is used, it should be proportional to the project's risk and ethical sensitivity. Information should not be unnecessarily long or detailed, even for complex research, and staged or tiered information may be used to address variation in participants' needs (NS 3.1.25).
Specific, extended and unspecified consent
The National Statement recognises that data or tissue collected in one project may be useful in later work, and it gives evaluators and researchers three consent options for this (NS 2.2.14):
- Specific consent is limited to the project at hand and is the default position. If a later project wants to reuse the data, researchers and evaluators must seek fresh consent or apply for a waiver (see When consent can be waived).
- Extended consent covers future use in projects that are an extension of, or closely related to, the original project, or that fall in the same general area of research or evaluation, for example a later evaluation round of a multi-year program (NS 2.2.14(b)).
- Unspecified consent covers use of the data or tissue in any future research or evaluation (NS 2.2.14(c)).
The necessarily limited detail available about future research or evaluation does not, by itself, disqualify extended or unspecified consent from being valid (NS 2.2.14). Where unspecified consent is sought, its terms and wide-ranging implications must be clearly explained to participants, and the terms of the consent given must be clearly recorded (NS 2.2.16). Any later application that relies on existing unspecified consent must describe the terms of that consent (NS 2.2.17), and any additional data or tissue that falls outside the scope of the original extended or unspecified consent still requires fresh consent or a waiver (NS 2.2.18).
Specific consent remains the appropriate default wherever it is achievable: it gives participants the clearest picture of what they are agreeing to and minimises later disputes about scope. Extended and unspecified consent are legitimate tools where there is a genuine, articulable rationale for anticipated future use and that rationale is documented at the time consent is sought, not retrofitted later.
Renegotiating and withdrawing consent
In complex or long-running projects, or where participants face increased risk, consent may need to be renegotiated or reconfirmed as the research progresses. Participants must be told of any change to the terms they originally agreed to and given the opportunity to continue or withdraw (NS 2.2.8). Participants are entitled to withdraw at any stage, and must be told about the consequences of, and procedure for, withdrawal before they consent (NS 2.2.6(g), 2.2.19-2.2.20). See Withdrawal of consent for what this entitlement does and does not guarantee in practice.
Where others are involved in the decision
Where a potential participant lacks capacity to consent, a person or statutory body with lawful authority must be given the relevant information and decide on the participant's behalf, in a manner that is not contrary to the participant's best interests; capacity can fluctuate and should be reassessed accordingly (NS 2.2.12). Within some communities, decisions about participation may properly involve families, community elders or formally constituted bodies as well as the individual (NS 2.2.13). See Consent in different contexts for how these considerations apply in practice, and People with disability or illness (NS 4.5), Children and young people (NS 4.3), and Aboriginal and Torres Strait Islander peoples (NS 4.7) for population-specific guidance.
Related resources
This page was last updated on 16 September 2026.
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This article makes reference to the National Statement on Ethical Conduct in Human Research 2025. It is intended as practical guidance and does not constitute legal advice.
AI Disclosure: Resources in this library were prepared using Large Language Models with input from Iris Ethics staff who guided the scope and design. Subsequent revisions and final versions were developed and approved by Iris Ethics staff.