Legally Authorized Representative (LAR)

A legally authorized representative (LAR) is the person (or, less commonly, judicial or institutional body) permitted to give informed consent to research participation on behalf of a prospective subject who cannot consent for themselves — most often because of a medical emergency, a cognitive or psychiatric condition that impairs decision-making capacity, or because the subject has died and the research involves their data or biospecimens. This guide covers what the term actually means under the regulations, who qualifies, and how IRBs and study teams handle it in practice. It assumes you already understand the baseline informed consent framework; for that foundation, see Informed Consent in Research, The 4 Principles of Informed Consent, and The Components of Informed Consent. This page picks up the narrower question of who may consent for someone else, and under what authority.

How the Regulations Define “Legally Authorized Representative”

The Common Rule, at 45 CFR 46.102(i), defines a legally authorized representative as:

“an individual or judicial or other body authorized under applicable law to consent on behalf of a prospective subject to the subject’s participation in the procedure(s) involved in the research. If there is no applicable law addressing this issue, legally authorized representative means an individual recognized by institutional policy as acceptable for providing consent in the nonresearch context on behalf of the prospective subject to the subject’s participation in the procedure(s) involved in the research.”

FDA’s parallel regulation, 21 CFR 50.3(l), uses essentially the same substantive definition for FDA-regulated clinical trials (drugs, biologics, and medical devices): an individual or judicial or other body authorized under applicable law to consent on behalf of a prospective subject. In practice, IRBs and study teams treat the two definitions as functionally equivalent, and most institutional policies apply a single LAR determination process regardless of which regulation governs a given study.

Two things in that definition do the real work, and both trip people up:

“Authorized under applicable law” comes first. The regulation does not hand IRBs or study teams discretion to pick whoever seems most appropriate — it defers to whatever state (or, for non-US sites, other jurisdiction’s) law already says about who may consent to medical procedures on someone else’s behalf. That is almost always the same body of law that governs healthcare decision-making generally: surrogate consent statutes, health care power of attorney / durable power of attorney for health care law, and guardianship or conservatorship law.
Institutional policy is a fallback, not a first option. The “if there is no applicable law” clause only kicks in when the relevant jurisdiction’s law is genuinely silent on the question. It is not a shortcut around inconvenient state law — IRBs are expected to determine what the applicable law actually says before relying on institutional policy.

The practical consequence: who legally qualifies as an LAR is a state-law question, not a uniform federal one. A person who may consent for an incapacitated relative in one state may not automatically have that authority in another — which matters directly for multi-site studies (see below).

Who Typically Qualifies as an LAR

Because the underlying authority comes from state law rather than the Common Rule itself, the exact list of who qualifies — and in what order of priority — varies by jurisdiction. That said, most states’ surrogate consent and health care decision-making statutes follow a broadly similar pattern, prioritizing roughly in this order:

A health care agent named in a valid health care power of attorney or advance directive executed by the subject while they had capacity.
A court-appointed legal guardian or conservator with authority over the subject’s health care decisions.
A spouse or domestic partner.
An adult child.
A parent.
An adult sibling.
In some states, a close friend or other person familiar with the subject’s wishes, values, and beliefs, where no one higher in the hierarchy is available.

This is a general pattern for orientation, not a substitute for checking the actual statute in the state(s) where a study is conducted — IRBs of record and study teams need to confirm the specific hierarchy, documentation requirements, and any research-specific limitations that apply locally. Some states’ surrogate consent laws authorize a representative to make medical treatment decisions but say little or nothing about research participation specifically, which is exactly the gap the “applicable law” language in 45 CFR 46.102(i) is written to address, and exactly where institutional policy or additional IRB scrutiny often has to fill in.

LAR vs. Related Terms: Guardian, Health Care Proxy, Power of Attorney

These terms get used loosely and interchangeably in casual conversation, but they are not identical, and an IRB reviewing a protocol involving adults who may lack capacity needs to know which one actually applies:

Legally authorized representative is the research-regulatory term — it is who the Common Rule or FDA regulations recognize as competent to consent to research participation specifically.
Health care agent / health care proxy is a person named in an advance directive to make medical treatment decisions. Whether that authority extends to research participation depends on the state statute and the specific language of the directive — some explicitly exclude research, some are silent, and some explicitly include it.
Legal guardian or conservator is court-appointed and typically has the broadest, most clearly documented authority, but the scope (health care decisions specifically vs. general financial/personal affairs) still needs to be checked against the actual court order.
Durable power of attorney for health care is the legal instrument that creates a health care agent; it is the document, not the person.

An LAR determination should always identify which of these underlying mechanisms is being relied on, and the IRB-approved consent process should specify how the study team will verify it — a signed advance directive, letters of guardianship, or documentation of the applicable statutory hierarchy where no formal instrument exists.

How This Differs from Parental Permission for Children

It is worth flagging one common point of confusion: research involving children is governed by Subpart D of the Common Rule, which uses the terms parent and guardian giving permission, not the LAR framework. The two concepts serve a similar practical function — someone consents on behalf of a person who cannot legally consent for themselves — but they arise from separate parts of the regulation, with separate definitions and separate documentation requirements. LAR applies to adults who lack decision-making capacity (or who are deceased, for research involving their data or specimens); parental/guardian permission applies to minors. See Vulnerable Populations Under the Common Rule for how both categories fit into the broader Subpart B/C/D structure, and how assent (the child’s own affirmative agreement) works alongside parental permission.

Why This Matters for Multi-Site Studies

Because LAR eligibility is a matter of state (or other jurisdiction’s) law rather than a single federal standard, a multi-site study can legitimately have a different answer to “who may serve as the LAR” at each site, even under a single reviewing IRB. This is one of the specific things a single IRB (sIRB) arrangement does not eliminate: while a central IRB can review the protocol and consent documents once, local site teams — or local counsel — still need to confirm the applicable state law on surrogate consent, and any local-context differences typically get documented as part of the reliance arrangement rather than absorbed into a single national answer. See Central IRB / Single IRB (sIRB) and SMART IRB Reliance Agreement for how that division of responsibility is typically documented.

Documentation and IRB Review Expectations

When a protocol anticipates enrolling subjects who may need an LAR — common in emergency medicine, critical care, dementia and cognitive-impairment research, and psychiatric research during acute episodes — IRBs generally expect the protocol and consent process to address:

How capacity will be assessed. A documented process for determining that a prospective subject genuinely lacks the capacity to consent for themselves, rather than assuming it from diagnosis alone.
Who may serve as LAR, in what order. A hierarchy consistent with the applicable state law, specified in the protocol rather than left to ad hoc determination at enrollment.
How LAR status will be verified and documented. What documentation (advance directive, guardianship papers, or a signed attestation of relationship and priority under the statutory hierarchy) the study team will collect and retain.
What happens if the subject regains capacity. Many protocols involving temporarily incapacitated subjects (e.g., emergency or ICU research) build in a re-consent step once the subject can consent for themselves, since the LAR’s authority was a substitute for the subject’s own, not a replacement for it going forward.
Whether a waiver applies instead. Some emergency research qualifies for an exception from informed consent (planned emergency research) or another consent waiver rather than relying on an LAR at all — these are governed by different, narrower regulatory provisions and should not be conflated with the LAR pathway. See Waiver of Informed Consent (45 CFR 46.116(f)) for the separate waiver mechanism.

The Informed Consent Checklist for Researchers and The Informed Consent Process in Clinical Trials: Step by Step both cover where LAR determination fits into the overall consent workflow for teams building out a protocol from scratch.

Frequently Asked Questions

Can a friend serve as a legally authorized representative?

In some states, yes — a subset of state surrogate consent statutes include a close friend familiar with the subject’s wishes and values as an eligible representative, typically only when no one higher in the statutory hierarchy (spouse, adult child, parent, sibling) is reasonably available. This is state-specific and should never be assumed without checking the applicable law.

Does an LAR’s authority ever expire or get revoked?

Yes. If the subject regains decision-making capacity, their own consent (or refusal) takes precedence going forward — this is why protocols enrolling temporarily incapacitated subjects commonly build in a re-consent step. A guardianship can also be modified or terminated by the court that established it, and a health care power of attorney can be revoked by the person who executed it while they had capacity to do so.

Is an LAR the same thing as next of kin?

Not necessarily. “Next of kin” is a general term describing closest living relatives and is not itself a legal consent standard. Whether a specific next-of-kin relationship (spouse, adult child, parent, sibling) confers LAR authority depends entirely on where that relationship falls in the applicable state’s surrogate consent hierarchy — and some states require a court-appointed guardian in circumstances where others would accept a next-of-kin declaration.

Does the LAR framework apply to research using a deceased person’s data or biospecimens?

The Common Rule’s human subjects protections generally stop applying once a subject has died, since the regulatory definition of “human subject” requires a living individual. However, an LAR (or, in some frameworks, a personal representative of the estate) may still be asked to consent or authorize use of a decedent’s data or specimens under separate authorities — most commonly HIPAA’s provisions on personal representatives, or institutional policy — which is a distinct question from Common Rule LAR consent and should not be assumed to work identically.

Key Takeaways

An LAR is authorized under applicable state (or other jurisdiction’s) law first, and only under institutional policy where that law is silent — not the other way around.
The Common Rule (45 CFR 46.102(i)) and FDA regulations (21 CFR 50.3(l)) define the term almost identically.
Who qualifies, and in what priority order, differs by state — protocols and consent processes need to specify and document the applicable hierarchy rather than assume a uniform national answer.
LAR consent for adults is a distinct regulatory pathway from parental/guardian permission for children (Subpart D) and from consent waivers under 45 CFR 46.116(f) — don’t conflate the three.
Multi-site studies under a single IRB still need site-level attention to which state’s surrogate consent law applies, since sIRB review does not override underlying state law.