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Overview
Full disclosure of a research project's aims or methods to participants can sometimes compromise the validity of the research itself, for example in studies of behaviour where knowing the true purpose would change how people act. NS 2.3 provides for "limited disclosure" in these circumstances, as a qualification of the general consent principle at NS 2.2, not a way around it.
Limited disclosure sits on a spectrum. At one end are minor omissions, such as not fully describing the aims of observational research conducted in public spaces. At the other end is active deception, where participants are affirmatively misled about the nature or purpose of the research. The National Statement treats these two ends of the spectrum differently, with active deception subject to stricter conditions.
Limited disclosure without active deception (NS 2.3.1)
A review body may approve limited disclosure that does not involve active concealment or planned deception where the researcher demonstrates all of the following (NS 2.3.1):
- no suitable alternative involving fuller disclosure would achieve the research aims;
- the potential benefits of the research justify both the limited disclosure and any risk to public trust in research and researchers;
- the research involves no more than low risk to participants and the limited disclosure is unlikely to affect them adversely;
- the precise extent of what is not being disclosed is defined; and
- whenever possible and appropriate, participants will, after their participation ends, be given an explanation of the research aims and why the omission was necessary, and be offered the opportunity to withdraw any data or tissue they provided.
A common example in market and commercial research is withholding the identity of the commissioning client from participants, for instance in a brand perception study. Participants know they are taking part in research; they simply are not told who is paying for it. This is comparatively low-stakes limited disclosure and does not involve active deception of participants.
Limited disclosure involving active deception (NS 2.3.2)
Where limited disclosure involves active concealment or explicit deception, and the research or evaluation does not aim to expose illegal activity, the researcher/evaluator must demonstrate, in addition to the NS 2.3.1 conditions, that (NS 2.3.2):
- participants will not be exposed to an increased risk of harm as a result of the concealment or deception;
- a full explanation of the real aims and methods, and of why the deception was necessary, will subsequently be made available to participants; and,
- there is no known or likely reason to think participants would not have consented had they been fully informed.
That last condition is decisive: deception cannot be used to secure participation from people who would otherwise have declined. Where the research or evaluation aims to expose illegal activity, additional requirements apply, and the adverse effects on those whose activity is exposed must be justified by the value of the exposure (NS 2.3.3; see Research that may discover illegal activity (NS 4.9)).
Only an HREC may review and approve research or evaluation that involves active concealment or planned deception, or that aims to expose illegal activity; these applications cannot proceed through a lower-risk review pathway (NS 2.3.4). See Lower risk vs full HREC review.
Debriefing
Where limited disclosure or deception is used, debriefing participants afterward is central to maintaining respect for them even though full disclosure was not possible upfront. Debriefing should explain what was withheld or how participants were misled, give the true purpose of the research or evaluation, and offer participants the opportunity to withdraw their data following debriefing (NS 2.3.1(e), NS 2.3.2(b)). See also Limited disclosure and deception in the Special techniques section for further detail on designing debriefing procedures.
Applying the test
Before proposing limited disclosure, ask whether it is necessary or merely convenient. Convenience is not a justification; the requirement is that the research aims cannot actually be achieved with fuller disclosure. Reviewers will look for a precisely defined scope of non-disclosure, a low-risk profile, and a credible debriefing plan, and will scrutinise applications that reach for deception where a fully disclosed design was available.
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.