03 · What You Need to Know
Voluntariness Is About the Conditions Surrounding the Decision
Voluntariness is one part of informed consent, not another name for it
The Belmont Report describes informed consent through three elements: information, comprehension, and voluntariness. A potential participant needs relevant information, must be able to understand that information adequately, and must be able to decide voluntarily.
These elements solve different ethical problems. Giving someone accurate information does not by itself make the decision voluntary. Likewise, a decision made without pressure is not adequately informed if the person does not understand what participation involves.
Informed
The person has received and adequately understood the information relevant to the decision.
Voluntary
The person's decision is made under conditions that permit a meaningful choice, without coercion or undue influence.
This distinction matters because a consent process can perform well on one dimension and poorly on another. A beautifully written information sheet cannot neutralize an authority relationship that makes refusal feel unsafe. Conversely, an entirely pressure-free invitation still requires enough understandable information for an informed decision.
A voluntary decision includes a real option to say no
Ethical standards do not require potential participants to be indifferent about participating. People can have strong reasons for saying yes. They may value the research, want access to a possible intervention, appreciate compensation, enjoy contributing to science, or simply find the study interesting.
The relevant issue is whether they retain meaningful freedom to choose otherwise.
The 2024 World Medical Association Declaration of Helsinki states that participation by people capable of giving informed consent must be voluntary and that potential participants must be informed of their right to refuse or withdraw without reprisal. CIOMS similarly describes informed consent as protecting a person's freedom of choice and requires researchers to provide sufficient opportunity and time to decide.
That makes the consequences of refusal especially important. If saying no could affect a grade, employment evaluation, access to ordinary services, clinical care, or another benefit to which the person is otherwise entitled, the apparent choice may be ethically compromised. The same concern can arise when no consequence has actually been threatened but the surrounding relationship makes one reasonably seem possible.
Pressure does not have to sound like a threat
The clearest cases are easy to recognize. “Participate or you will lose this service” is fundamentally different from an ordinary research invitation.
More difficult cases are quieter.
A professor sends repeated invitations directly to students. A manager asks employees individually whether they have completed the company study. A physician enthusiastically recommends joining their own trial. A community leader tells members that the researchers are expecting everyone's cooperation. None of these situations necessarily contains an explicit threat, yet each may change how free refusal feels.
Researchers therefore need to examine how power differences affect the practical freedom to refuse, not merely search recruitment materials for obviously threatening words.
Coercion and undue influence are related, but they are not interchangeable
The Belmont Report distinguishes coercion from undue influence. In its formulation, coercion involves a threat of harm used to obtain compliance, whereas undue influence involves an excessive, unwarranted, inappropriate, or improper reward or other overture. The boundary becomes more difficult because an otherwise acceptable inducement may have a different effect in a particular person's circumstances.
Ordinary persuasion is not automatically unethical either. Explaining why a study matters, answering questions, correcting misconceptions, and accurately describing potential benefits are compatible with voluntary decision-making. The ethical boundary depends on whether influence informs and supports a choice or improperly distorts it.
The distinctions deserve careful treatment because casually calling every incentive “coercion” obscures the actual ethical problem. Researchers evaluating a recruitment strategy should distinguish persuasion, undue influence, and coercion rather than treating them as synonyms.
Influence is not the same thing as undue influence
Almost every research decision is influenced by something. A clear explanation may influence someone to participate. Compensation may matter. A recommendation from a trusted person may matter. The convenience of the study may matter. So may curiosity, altruism, personal experience with the research topic, or the possibility of receiving a study intervention.
If voluntariness required a decision untouched by influence, virtually no human decision would qualify.
The more useful question is whether the influence is ethically problematic in the circumstances. OHRP notes that influence is contextual and that drawing a bright line around undue influence can be difficult. For example, compensation for research participation is generally acceptable, but its amount and conditions require ethical review because incentives can sometimes interfere with voluntary consent.
Watch Out
Do not evaluate voluntariness by asking only, “Did we threaten anyone?” A recruitment process may create ethically significant pressure through authority, dependency, incentives, repeated requests, social expectations, or perceived consequences even when nobody makes an explicit threat.
Who asks can matter as much as what is asked
The identical invitation can have a different meaning depending on who delivers it.
“Would you like to participate in my study?” may be a relatively uncomplicated request between strangers. Coming from someone's professor, employer, supervisor, clinician, service provider, or another person with authority over something the potential participant values, the same sentence may carry additional weight.
The current Declaration of Helsinki specifically calls for particular caution when potential participants are in a dependent relationship with the researcher or may consent under duress. For medical research in such circumstances, it states that informed consent must be sought by an appropriately qualified person independent of that relationship.
Dependency does not automatically make participation involuntary, nor does it necessarily mean the population must be excluded. It means the consent process may need safeguards that separate the research decision from the authority relationship. This becomes especially important when a supervisor or teacher wants to recruit people over whom they have authority.
What participants believe can matter even when the researcher intended no pressure
Researchers naturally know which activities are research, which are required, and which are optional. Potential participants may not share those distinctions.
Imagine a survey distributed during a mandatory staff meeting. The researcher says participation is voluntary. Everyone receives the survey from a manager, most colleagues begin completing it, and the manager remains in the room. The researcher may sincerely intend participation to be optional. An employee may nevertheless conclude that refusal will be noticed.
This does not mean every subjective feeling automatically establishes coercion. It does mean that ethical design should consider reasonably foreseeable perceptions created by the setting, relationships, and recruitment procedure. OHRP specifically recognizes that students may feel pressure when others in a class participate and that employees' choices can be affected by concerns about evaluations, advancement, benefits, or deference to authority.
Researchers should therefore respond when potential participants appear to believe that participation is mandatory, even if the consent document already contains the word “voluntary.”
Time and opportunity to decide are part of the ethical environment
A person may technically be allowed to refuse but have little practical opportunity to consider the decision. This is why major ethical frameworks pay attention to the circumstances in which consent is obtained.
CIOMS calls for sufficient opportunity and time to consider participation. U.S. HHS regulations similarly require circumstances that provide sufficient opportunity to consider whether to participate while minimizing coercion or undue influence. ICH E6(R3), for clinical trials, requires ample time unless otherwise justified and an opportunity to ask questions before deciding.
There is no universal ethical waiting period for every study. A short anonymous questionnaire and a complex interventional trial do not demand identical deliberation. What matters is whether the time and setting are appropriate to the decision being asked of the participant.
Voluntariness continues after the consent form is signed
Consent is better understood as a process than as a one-time administrative event. CIOMS explicitly describes informed consent this way and recognizes a participant's right to withdraw during the study without retribution. ICH E6(R3) also requires participants to receive new information that may be relevant to their willingness to continue and addresses re-consent when circumstances warrant it.
Someone who voluntarily joins a study is therefore not ethically committed to finish it simply because they signed a form, completed several sessions, received compensation, or would inconvenience the research team by leaving.
This is a useful test of a researcher's understanding of voluntariness: if a participant's initial “yes” is respected but their later “no” is treated as disloyalty, failure, or an obstacle to be overcome, voluntariness has been reduced to enrollment rather than respected throughout participation.
Voluntary does not mean consequence-free in every possible sense
The right to withdraw does not mean that researchers must pretend withdrawal has no practical implications. For example, a participant may stop receiving a research-only intervention after leaving a trial, and compensation may legitimately correspond to activities already completed rather than activities never performed. Depending on the study, data already collected may also be subject to applicable consent terms, law, regulation, protocol requirements, and ethics approval.
The central protection is different: researchers should not impose or threaten inappropriate penalties, retaliation, or loss of benefits to which the person is otherwise entitled merely because the person refuses research participation or decides to stop.
This distinction prevents “voluntary” from becoming an unrealistic promise while preserving what the concept is actually meant to protect: meaningful freedom over research participation.
04 · A Practical Example
When “Optional” May Not Feel Optional
Hypothetical Example
A faculty member recruits students from their own class
A researcher wants 80 university students for a questionnaire study. The easiest pool is the researcher's own class. Near the end of a lecture, the researcher distributes the study information and says, “This is completely voluntary, but I hope you can help me complete my research.” Students are asked to scan a QR code before leaving. The researcher remains at the front of the room while they decide.
What the researcher intended
Participation is optional, the study is low risk, and nobody has been explicitly threatened or ordered to join.
What a student may perceive
The invitation comes from the person who teaches or evaluates them. Declining is visible, and “I hope you can help me” may create a sense of personal obligation.
Where the ethical problem lies
The concern is not simply whether the consent form says “voluntary.” The recruitment setting combines authority, visibility, and an immediate request in ways that may make refusal more difficult.
What could change
Subject to ethics approval and institutional requirements, recruitment might be separated from the instructor, responses could be collected without the instructor knowing who participated, students could decide outside class, and any academic incentive could have a comparable non-research alternative.
What the example shows
Voluntariness is strengthened by changing the conditions of choice, not merely by adding stronger wording to the consent form.
The example does not establish that researchers can never study their own students. That question requires attention to the specific relationship, institutional rules, study design, and safeguards. The important point here is that recruiting one's own students creates particular voluntariness concerns that cannot be solved simply by declaring participation voluntary.
06 · What This Means for You
Design for a Free Choice Rather Than Merely Declaring One
When assessing voluntariness, shift the question from “Did we tell participants this was voluntary?” to “What would it actually be like for this person to say no?”
That change in perspective often exposes issues that consent language alone will miss.
A simple decision framework
If refusal could affect something the person already has a right to receive
Separate the research decision from that benefit and make the absence of penalty or reprisal clear.
If the recruiter has authority over potential participants
Consider whether recruitment or consent can be handled by an independent person and whether the researcher can be prevented from learning who declined.
If an incentive is important to recruitment
Assess its amount, conditions, population, and alternatives rather than assuming either that all payment is acceptable or that all payment is coercive.
If people appear to think participation is expected
Correct the misunderstanding and examine what in the recruitment setting created it.
If someone wants to stop after enrolling
Respect the withdrawal process described in the approved protocol and consent materials without retaliation or inappropriate pressure to remain.
The most effective safeguard will depend on the study. Anonymous online recruitment may require relatively little separation between researcher and participant. Research involving students, employees, patients, clients, institutionalized populations, or people dependent on services may require substantially more attention to relationships and context.
Recruitment deserves particular scrutiny because voluntariness can be weakened before a consent form ever appears. Researchers should therefore design recruitment procedures that minimize pressure from the beginning rather than expecting the consent process to repair a problematic invitation later.
Finally, remember that ethics review is contextual. Applicable laws, regulations, institutional policies, research ethics committee requirements, and disciplinary standards may impose additional safeguards. When in doubt, the appropriate response is not to improvise around an approved recruitment or consent process but to consult the relevant research ethics committee or institutional review board.
