An institutional review board (IRB) is a committee that reviews research involving people to protect their rights, safety, and wellbeing. Federal law requires any research institution conducting studies with human participants to have this independent oversight in place before a single volunteer is enrolled. The board reviews study plans, evaluates risks, and ensures that participants genuinely understand what they’re agreeing to.
The Core Purpose: Protecting Research Participants
Federal regulations define an IRB as any formally designated board or committee that reviews and approves research involving human subjects. Its primary purpose, stated directly in the Code of Federal Regulations, is “to assure the protection of the rights and welfare of the human subjects.” That means the IRB acts as a gatekeeper. No clinical investigation requiring federal submission can begin until the IRB has reviewed and approved it, and the study remains subject to the board’s continuing oversight for its entire duration.
This isn’t optional. Any institution that receives federal funding for research, or that conducts studies regulated by the FDA, must maintain an IRB or use an authorized one. The requirement covers everything from large clinical drug trials to university studies using surveys or behavioral observations.
The Ethical Principles Behind IRB Decisions
IRBs base their decisions on three ethical principles laid out in the Belmont Report, a foundational document published in 1979 by a national commission after serious abuses in research came to light.
Respect for persons means treating people as autonomous agents who can make their own decisions. It also means that people with reduced ability to make decisions for themselves, such as children or individuals with cognitive impairments, deserve extra protection. This principle is the moral basis for requiring informed consent.
Beneficence goes beyond simply avoiding harm. It requires researchers to actively minimize risks and maximize potential benefits. For an IRB, this translates into a practical question: are the risks of this study justified by the potential benefits to participants or to the knowledge that will be gained?
Justice addresses who bears the burdens of research and who receives its benefits. Historically, vulnerable groups like prisoners and low-income communities were disproportionately used as research subjects while wealthier populations reaped the medical advances. The justice principle requires that participant selection be fair and that no group be exploited for the benefit of another.
What the Board Actually Evaluates
Before approving any study, an IRB must confirm that seven specific criteria are met. These aren’t suggestions. Every one must be satisfied.
First, risks to participants must be minimized through sound research design. If a procedure is already being performed on someone for medical reasons, the study should piggyback on that rather than adding unnecessary exposure. Second, whatever risks remain must be reasonable compared to the anticipated benefits and the importance of the knowledge the study could produce. The board weighs only the risks and benefits of the research itself, not the risks of treatments participants would receive anyway.
Third, the selection of participants must be equitable. The IRB pays special attention when a study involves people who could be vulnerable to pressure or coercion, including children, prisoners, people with impaired decision-making capacity, and economically disadvantaged individuals. Fourth and fifth, the board verifies that informed consent will be properly obtained and documented. Sixth, when appropriate, the research plan must include provisions for monitoring data to ensure participant safety as the study progresses. Seventh, there must be adequate protections for participants’ privacy and the confidentiality of their data.
How Informed Consent Works
One of the IRB’s most visible responsibilities is reviewing the consent process. A valid consent document must include several specific elements: a clear statement that the study involves research, an explanation of the study’s purpose and how long participation will last, a description of what participants will actually be asked to do, and identification of anything experimental.
Beyond that, the document must describe foreseeable risks or discomforts, any expected benefits to the participant or others, and alternative treatments or procedures that might be available. Participants must be told how their records will be kept confidential, who to contact with questions or if they’re injured, and that their participation is entirely voluntary. That last point is critical: participants must understand they can quit at any time without losing any benefits they’d otherwise be entitled to.
A 2018 update to federal rules, known as the revised Common Rule, added a new expectation. Consent forms must now begin with a concise summary of the key information a person would need to decide whether to participate, including the study’s purpose, its risks and benefits, and any alternative treatments. This was a direct response to the reality that consent forms had become dense legal documents that few people actually read or understood.
Three Levels of Review
Not every study goes through the same review process. Federal rules establish three tiers based on the level of risk involved.
Exempt review applies to research that poses very little risk, such as educational tests, anonymous surveys, interviews, or observation of public behavior. Studies in this category don’t require continuing review or formal reporting of problems. A “limited IRB review” may still be needed to confirm the exemption applies, but the oversight burden is intentionally light.
Expedited review is for studies that involve no more than minimal risk, meaning the probability of harm is no greater than what people encounter in daily life or during routine medical exams. The study must also fit into one of nine predefined categories. A single experienced IRB member, typically the board chair or a designee, can review and approve these studies without convening the full committee.
Full board review is required for everything else. Any study that doesn’t qualify as exempt or expedited goes before the entire committee at a convened meeting. This includes most clinical trials, studies involving more than minimal risk, and research with vulnerable populations.
Who Sits on an IRB
Federal regulations require each IRB to have at least five members with diverse backgrounds. The board must include at least one person whose expertise is in a scientific field and at least one member whose primary concerns are nonscientific, such as an ethicist, lawyer, or community member. At least one member must have no affiliation with the institution at all, providing an outside perspective free from institutional pressures.
The regulations also call for diversity in race, gender, and cultural background, along with sensitivity to community attitudes. This composition is deliberate: it prevents any single viewpoint from dominating decisions about what risks are acceptable for other people to bear.
Extra Protections for Vulnerable Groups
Federal regulations include additional subparts that impose stricter rules when research involves populations considered especially vulnerable.
For research involving pregnant women or fetuses, if there’s no prospect of direct benefit to the fetus, the risk must be no greater than minimal, and the research must aim to produce important knowledge that can’t be obtained any other way. When a study might benefit the fetus directly, both parents generally must consent.
For prisoners, the IRB must include at least one member who is a prisoner or a prisoner representative. The board must also ensure that parole decisions won’t be influenced by whether someone participated in a study, and participants must be told this explicitly.
For children, the IRB must confirm that the study includes appropriate provisions for getting the child’s own agreement (called assent), taking into account their age, maturity, and psychological state. For higher-risk studies, both parents typically must give permission unless one is deceased, unknown, or unavailable.
Ongoing Oversight After Approval
An IRB’s job doesn’t end once a study is approved. Federal regulations require continuing review at least once a year for the life of the study. For higher-risk research, the board can mandate more frequent check-ins. During continuing review, the IRB examines progress reports, any unanticipated problems, and whether the risk-benefit balance has shifted since the original approval.
Researchers must also report any changes to their study protocol to the IRB before implementing them. The only exception is a change needed to eliminate an immediate hazard to participants, which can be made first and reported afterward. If a study’s approval lapses without renewal, all research activity must stop.
When unanticipated problems involving risks to participants arise, the institution’s procedures must ensure these are reported to the IRB promptly. If participants are still enrolled, the board can require investigators to inform them of new risks and can suspend or terminate a study that no longer meets approval criteria.
Single IRB Review for Multi-Site Studies
When the same study runs at hospitals or universities across the country, having every site conduct its own full IRB review created enormous delays and redundancy without meaningfully improving participant protections. In response, NIH now requires that all domestic sites in a federally funded multi-site study use a single IRB of record. This policy, which applies to grants, cooperative agreements, contracts, and intramural research, eliminates duplicate reviews while still requiring that each participating site communicate local context and state-specific regulatory requirements to the reviewing board. The goal is straightforward: get research moving faster without cutting corners on oversight.