03 · What You Need to Know
The word "legally" does most of the work in LAR
HHS and FDA use closely aligned definitions
Under the U.S. Common Rule, an LAR is an individual or judicial or other body authorized under applicable law to consent on behalf of a prospective participant to participation in the procedures involved in the research. FDA defines the term similarly for clinical investigations.
ICH E6(R3) uses the term legally acceptable representative, defined as an individual or juridical or other body authorized under applicable law to consent on behalf of a prospective participant to participation in the clinical trial.
Legally authorized representative
The terminology used in U.S. HHS and FDA frameworks for a representative authorized under applicable law to provide research consent on another person's behalf.
Legally acceptable representative
The corresponding terminology used in ICH E6(R3) for clinical trials, likewise grounded in authority under applicable law.
The exact terminology varies, but researchers should always verify the definition used by the framework governing their study.
Who qualifies as an LAR depends on applicable law
OHRP states explicitly that the identity of an LAR is determined by the laws of the jurisdiction in which the research is conducted. Some jurisdictions have statutes, regulations, or case law specifically addressing research consent by another person. Others do not.
Where research-specific law is absent, OHRP notes that laws governing consent to medical treatment or particular medical procedures may sometimes provide a reasonable legal basis for determining who can consent to the research procedures involved. IRBs may need legal counsel when making that determination.
Watch Out
Do not build a universal hierarchy such as spouse, then adult child, then sibling unless the law and institutional procedure governing your research actually establish that hierarchy. Rules from one jurisdiction should not be copied into another simply because they seem familiar.
An LAR is not simply the participant's next of kin
Next-of-kin status and legal research-consent authority may overlap, but they are not synonymous.
A spouse may qualify under applicable law. An adult child may qualify. A guardian or another appointed decision-maker may qualify. But none of those conclusions can be made universally from the relationship label alone.
Similarly, an emergency contact is simply someone designated for contact unless some separate legal authority applies. Listing a person on a hospital form does not automatically authorize that person to enroll the patient in research.
A healthcare proxy or power of attorney requires attention to scope
A person may hold authority to make healthcare decisions for someone else. Whether that authority extends to research participation can depend on the wording of the instrument and applicable law.
OHRP emphasizes that the representative must be authorized under applicable law to consent to the prospective participant's participation in the procedures involved in the research.
The question is therefore not merely whether a document called a power of attorney exists. Researchers and institutions may need to determine whether the authority it grants covers the decision at issue.
A guardian's authority may also have limits
Court-appointed guardianship can vary in scope. One guardian may have broad authority over personal or healthcare decisions; another may have authority restricted to financial matters or particular decisions.
Researchers should therefore follow institutional procedures for verifying both the existence and scope of guardianship rather than treating the word "guardian" as automatically dispositive.
An LAR becomes relevant because the participant cannot provide the required consent
The existence of a possible LAR does not mean researchers should automatically obtain consent from that person.
If the prospective participant has adequate capacity to provide their own legally effective consent, their decision should ordinarily be sought directly. OHRP states that LAR consent becomes relevant when an adult lacks capacity to consent, subject to applicable law and any authorized waiver of informed consent.
This makes the prior question of assessing the participant's consent capacity particularly important.
Having an LAR does not make every study ethically appropriate
Representative permission is one safeguard. It is not a universal ethical license to enroll people who cannot consent for themselves.
Research involving participants with impaired decision-making capacity may require additional protections based on the applicable regulations, ethics framework, risk, expected benefit, scientific necessity, and participant population.
The 2024 Declaration of Helsinki, for example, places conditions on medical research involving people incapable of giving free and informed consent and requires legally authorized representative consent while also addressing assent, dissent, and circumstances in which research with that population is permissible.
An LAR's signature therefore answers only part of the ethical question.
The LAR must receive the informed consent information
FDA regulations require consent information given to the participant or representative to be understandable and consent to be sought under circumstances providing sufficient opportunity to consider participation while minimizing coercion or undue influence.
ICH E6(R3) similarly defines informed consent as a process in which the participant or legally acceptable representative voluntarily confirms willingness to participate after being informed and given an opportunity to discuss aspects of the trial relevant to the decision.
The LAR therefore needs an actual informed consent process. Handing a relative a signature page after saying "the patient cannot consent" is not enough.
The participant still has a role
Representative consent should not unnecessarily displace the participant from the decision. A person who lacks full consent capacity may still understand some study information, express preferences, assent, or object.
Research frameworks vary in their precise requirements, but ethically the participant should generally be involved to the extent possible. The Declaration of Helsinki requires assent from participants incapable of giving free and informed consent when they are able to assent and states that dissent should be respected.
This becomes especially important if the participant and representative disagree about participation.
The LAR's authority is tied to the participant's need for representation
If a participant regains or develops adequate consent capacity, the basis for relying on representative consent can disappear.
OHRP states that when a participant regains or develops capacity to consent, the participant's own consent must be obtained for further research because the LAR's consent is no longer valid as a substitute.
Research involving temporary or fluctuating incapacity should therefore plan for reassessment and reconsent rather than assuming the LAR remains the decision-maker indefinitely.
An LAR is different from a witness
A witness does not ordinarily make the participation decision. The witness observes or attests to aspects of the consent process required by a particular procedure.
For example, ICH E6(R3) requires an impartial witness during the informed consent discussion when the participant or legally acceptable representative cannot read. The witness attests to the consent process; the participant or representative remains the decision-maker.
LAR
Has legal authority, when applicable, to make the research participation decision on behalf of the prospective participant.
Witness
Observes or attests to specified aspects of the consent process but does not acquire decision-making authority merely by witnessing it.
An LAR is also different from an interpreter
An interpreter facilitates communication. They do not become legally authorized to decide for the participant merely because they translate the consent discussion.
A relative could theoretically occupy more than one role if the governing framework permits it, but researchers should establish each role separately rather than allowing "family member" to become an all-purpose category for interpreter, witness, and decision-maker.
Children usually involve parental permission rather than ordinary adult LAR rules
Under HHS regulations governing research involving children, permission of parents or guardians and assent of children are addressed through child-specific requirements. OHRP defines children according to the legal age for consent to the treatments or procedures involved in the research under applicable jurisdictional law.
Researchers should therefore use the framework applicable to the participant population rather than referring generically to every person making a decision for someone else as an LAR.
07 · A Quick Checklist
Before accepting consent from an LAR
Before the representative signs, check:
Confirm that the participant cannot provide the required legally effective consent at this time.
Verify that representative consent is permitted for the study and participant population.
Identify the law of the jurisdiction governing who may serve as the representative.
Verify the representative's identity, legal basis, and scope of authority using the institution's approved procedure.
Do not assume that spouse, next-of-kin, caregiver, emergency-contact, guardian, or healthcare-proxy status automatically answers the research-consent question.
Provide the LAR with the complete informed consent process required for the research.
Provide the participant with information appropriate to their abilities and address assent or dissent as required.
Document representative authority and consent according to the approved protocol and institutional requirements.
Reassess the participant when capacity may return and obtain their own consent when required.
